The Cheyenne Mountain Air Station, which houses the North American Aerospace Defense Command, tested the system last week, interfering with garage door openers all across the area. "They have turned it off to be good neighbors," Air Force Capt. Tracy Giles told the Associated Press.

In general, effects from the transmissions would be felt only within 10 miles, but the Colorado Springs signal is beamed from atop 6,184-foot Cheyenne Mountain, which likely extends the range.

Holly Strack, who lives near the entrance to the facility, said friends in the neighborhood all had the same problem.

"I never thought my garage door was a threat to national security," she said. - Associated Press

The system has also been tested at Eglin Air Force Base, Fla.; the Defense Distribution Depot Susquehanna near New Cumberland, Pa.; and Ft. Detrick, Md., resulting in thousands of complaints, according to a 2005 Government Accountability Office report (PDF).

If the Air Force is unable to resolve the interference by retuning their system, homeowners would have to replace their garage door openers with devices that use different frequencies. Under Federal Communications Commission rules, unlicensed devices such as garage door openers must accept any interference received from licensed users of a frequency.

For longstanding Debrett's readers, who might normally use the book for advice on addressing the wife of a son of a baron, it is likely to be quite an eye-opener.

In addition to tables helping them speak the Queen's English (Salisbury should be pronounced "Sawls-bri", by the way) they will find chapters headed Teleconferencing and Mobile Phones.

Next to a chapter on how to address a King or Queen ("Your Royal Highness" for the first time and subsequently "Sir" or "Ma'am" as appropriate) lies a beginners' guide to text-messaging: "A quick and efficient method of communication, usually sent from one mobile phone to another."

The advice offered by Debrett's covers everything from the mundane to the potentially explosive. Readers are warned, for example, that: "Text messages cannot be secured, or the distribution limited. They can be stored indefinitely and propagated at whim." They are also sternly cautioned that: "It is unacceptable to read a text message sent to another person's mobile phone. It is equally unacceptable to send a text from another person's mobile phone."

Yet many of Correct Form's new chapters aim to offer common-sense advice to help committed Luddites come to terms with the onward march of Progress. "Teleconferencing is constrained by the lack of facial expressions and body language," reads one such entry. "It is therefore important to speak distinctly and keep the tone of voice modulated."

Although the revelation that Debrett's has embraced digital technology is likely to set moustaches twitching among traditional readers, the firm is adamant that it must move with the times.

"With all matters of etiquette, things change," says the company's chairman, Conrad Free. "Some of this technology hasn't been around for a long time, but it is still right that people use it in the correct manner. People still listen to Debrett's. Many people in the UK use Correct Form as a reference book on a regular basis, and as the voice of authority on how to behave, we have to evolve."

In general, the modern gent is advised to reply to an invitation or message in the medium in which it was originally sent, and if in doubt to err on the side of formality when communicating via new technology.

E-mail etiquette is an art in itself, yet the most socially intrusive, and therefore potentially dangerous, modern gadget is, unsurprisingly, the ubiquitous mobile telephone. "We've all sat there on a train or in a restaurant with people bellowing into a mobile phone, and it can be very annoying," says the book's editor, Jo Aitchison. "Equally, with ring tones, putting a phone on silent or vibrate is generally the way forward. If you really want a novelty ring tone, then I suppose you can have one, but for goodness sake answer it quickly, and we would advise having an alternative 'ring ring' one for work."

As a general rule of thumb, though, it's all about having consideration for others. In both "E-tiquette" and etiquette, she adds: "The number-one rule is to treat others as you would like to be treated."

Think Before You Use The 'BCC' Field

"Blind carbon copy", or "bcc", should seldom be used; it is deceptive to the primary recipient. Instead, the e-mail should be forwarded on to the third party, with a short note explaining any confidentiality, after its distribution. If blind copying is essential - for example, for a confidential document where all recipients must remain anonymous - senders should address the e-mail to themselves, and list all recipients as "bcc" recipients. The recipients will be aware that the full distribution list has been hidden from them.

Avoid Writing A Pointless Subject Field

The subject line is a summary of the content of the e-mail, and should alert the recipient. A well-written subject line will ensure that the e-mail gets the appropriate attention. It is also used for filing and retrieval purposes, so it is important that it accurately reflects the topic of the e-mail.

Should You Send A Letter Instead?

Written correspondence must never be replied to solely by e-mail. If an urgent response is necessary, then a telephone call or an e-mail is acceptable, but only provided it is followed up with the appropriate written correspondence.

Use Proper Punctuation

Ensure that correct punctuation is used, and do not succumb to the habit of using lower case letters throughout.

Don't Waste People's Time

As with letters, it is polite to reply to e-mails promptly. A few words suffice as a holding reply (and reassure the sender that the e-mail has been received) until a longer reply can be composed.

Include Your Contact Details

It is common to have a choice of several professional and informal signatures. Business e-mail signatures should supply relevant information, such as job title, company website address, telephone and e-mail address.

Salutation And Sign-Off

Suggested informal salutation: name only (ie, "Jon"). Informal sign-off: "See you soon". Formal salutation: "Dear Mr Davenport". Informal salutation: "Kind regards". Err towards the formal.

Refrain From Sarcasm

Unlike an interactive telephonic or face-to-face conversation, it is impossible to judge how the recipient will interpret any comments in an e-mail. The writing should therefore be kept brief, simple and to the point. Any sarcasm or subtle humour must be tempered, especially in messages sent between those who are less well-acquainted.


Correct Form is published by Debrett's, priced £17.99

Residents told how they ran in terror from their houses in Whitmore Gardens and Chamberlayne Road in Kensal Rise as the tornado struck. Miko Adam said: "There were some lightning strikes and then suddenly, out of nowhere, this cyclone whipped up. It was terrifying. I was in my attic and had to crawl under the bed up there.

"It only lasted about 10 seconds but they were the longest of my life. I never thought I would experience this kind of weather in this country," he said.

"My neighbour Fiona had the entire side of her house ripped off. She ran out into the road after it happened and was screaming." Mr Adam said about six houses had been badly damaged and another 20 or so had missing chimney stacks, roof tiles and garage walls. On the two streets in the path of the tornado trees were uprooted, and cars flung about.

A spokesman for the Met office said: "From about 11am what we call a squall line has been passing through north-west London. "When the clouds are well ordered in a clear line it can lead to tornadic activity."

Tim Klotz, who works in entertainment and film and has recently moved to the street, said it happened right in front of his house.

He said: "It was like some sort of cyclone. I was actually in an attic room working at my desk on the computer and there was heavy rain and sleet and then the wind just really changed.

"I looked up through a skylight and debris was falling through the air. I heard what seemed like large, clay dominoes falling, which I think were roof tiles."

The 34-year-old, originally from New York, said it then went "a bit dark" so he went downstairs and heard a smash at the front of his house.

He said: "My house was very lucky because there was only a broken window and some damaged roof tiles, but another house had its roof peeled off and fences had come down along the street.

"It was right in front of my house. I must have been right in the middle of it. There are police and fire services here now but I cannot see any fires."

A spokesman for weather forecaster MeteoGroup said a band of strong storms came through, with Heathrow Airport recording gusts of 48 knots (55mph).

He said: "That is quite squally so residential areas might have had gusts of up to 60mph.

"It still seems to be very localised so it is either what is called a micro burst - a strong down-burst of wind - or a tornado, which is when the wind goes up."

Local resident Daniel Bidgood told BBC London 94.9: "I've witnessed my first tornado.

"I was in my living room and I heard a big crack of lightning and thunder, then as I went to the window I heard a sound which was like standing behind a jetliner.

"I could see a huge cloud rolling up the street, making this tremendous sound.

"I went to try to take a picture of it but a shower of debris smashed all the windows of my house."

Colin Brewer, who lives in nearby Trevelyan Gardens, told the BBC: "It was really, really incredible. All of a sudden I saw a swirl starting to form and then, it was amazing, but it then touched land.

"I then saw clumps of all sorts of things flying into the air."

He reported seeing trees collapsed in the road and people being hit on the head by flying objects.

ondon Fire Brigade said it had sent 11 fire crews and around 50 firefighters to the scene.

Fire engines from stations including Paddington, Soho, Kentish Town and Kensington fire stations were sent.

Dawn Butler, the Labour MP for Brent South, told Sky News: "We have to try and make sure that those people who are put out and not able to get their belongings that it does not have a detrimental effect upon their Christmas.

"But we also should be grateful that nobody has been fatally injured and that no lives are lost.

"This is a mini tornado and look at the damage it has done. It has done maximum damage." She believes the tornado is a sign that climate change is having an effect.

Ms Butler said: "This is a sign that we have to take it seriously and we have to look at how we live our lives. It is quite devastating." Emergency services are currently on the scene, securing the area.

Ms Butler added: "We have to leave it to the experts. I would suggest that nobody try to go back in. It is material belongings. Our first priority has to be that residents are safe and the area is secure. We don't want another disaster, we have already got one."

Ms Butler is set to talk to local hotels to try to ensure that displaced residents have shelter.

Showroom manager Darma Vaja said it was "like a minor explosion" and no- one realised what it was.

Recalling the moment when the tornado hit, he told Sky News: "There was a sudden gush of wind, it was quite powerful. The next minute it started clearing up and we saw the commotion outside.

"There were people walking down the street saying it was some sort of blast and did not know what had happened. Then the police told us.

"There was debris on both sides of the Chamberlayne Road. There were roof timbers on the floor and roof tiles all over the place. You could see on the school opposite some of the roof tiles had been blown off."

He spotted that the side wall of one house had been completely knocked out. He said: "It looked like it was about to be demolished, you can see the internals of the house very clearly. The pitched roof of the house had been completely blown away."

Maya Sendall, an actress, said she was on the phone to a friend when the tornado ripped up the street.

She said: "I carried on with my phone call but as it came past I was absolutely shrieking with shock. It sounded like a train going by and it shook the house.

"I saw the rubbish bin going by and my hedge flattened by about two or three feet. I did not hear too much of the crashing because the sound of the wind was astonishing.

"I was four houses away from having the roof ripped off basically. I just could not believe my luck."

Julia Haughton, 22, a student, heard the tornado from inside her boyfriend's house on Crediton Road.

She said: "There was a thunder clap and it felt like the house was falling in on us. It was really frightening. My boyfriend came running in saying it was a tornado. He ran out just as it had gone through our back yard and pulled down our neighbour's tree. When I came out all the windows were smashed."

The Association of British Insurers (ABI) said it was too early to estimate the cost of damage caused by today's tornado.

However, a spokesman said damage caused by the Birmingham tornado in 2005 ran into "tens of millions of pounds".

He said damage caused to homes and businesses today would be covered by buildings insurance. Most household policies would cover the cost of alternative accommodation, up to the policy's limit, if residents needed to move out while repairs were carried out.

Damage to vehicles would be covered under comprehensive motor insurance, the ABI said. A spokesman advised those who had suffered damage to contact their insurer for advice on making a claim.

He said people should arrange for temporary repairs to stop damage worsening if necessary, and to keep all receipts as they would form part of any insurance claim.

He has now been allowed to leave leave Southampton General Hospital for weekend visits, and his delighted parents have hailed his amazing recovery.

Mum Debra, 40, said: "I was watching the race and I just felt physically sick. I could see the impact, how fast he was going.

"At first I wasn't really sure about the extent of his injuries. He had been knocked out but came round and stayed awake while they cut him out of the car.

"He is very lucky to be alive. It's a miracle really."

She said Chris, from Fareham, now wants to get back behind the wheel, adding: "He has no chance. I can't go through that again."

The remarkable observations demonstrate for the first time that modern Mars may not be as dry and barren as is usually assumed. Wherever liquid water is found on Earth there is also life, and most scientists consider its presence a prerequisite for the existence of primitive extraterrestrial organisms. If it exists on Mars, it raises the very real prospect that life may not only have evolved there in the past, but could survive there today.

Ice has been detected at the Martian poles, and many of the planet's features are known to have been formed by water in the distant past. But there have been few firm indications that it is present today, in liquid form. That has changed with the latest images from Nasa's Mars Global Surveyor spacecraft. Between 1999 and last year, it took pictures of thousands of gullies, which have since been examined for significant change.

At two sites, the Terra Sirenum crater and an unnamed second crater in the Centauri Montes region, channels were seen in later images containing fresh, pale-coloured deposits that appear to have been left by flowing water.

At Terra Sirenum, the image changed dramatically between December 2001 and April 2005, and at Centauri Montes the changes happened between August 1999 and February 2004. The character of the deposits left by whatever cascaded briefly down these slopes, particularly the way it has flowed around solid obstacles, points firmly towards water rather than dust as the cause of the new features.

"The observations suggest that liquid water flowed on Mars during the past decade," Mike Malin, chief scientist for the camera that took the pictures, said. In each case, the amount of water that formed the features would have been approximately equivalent to five to ten swimming pools full, Michael Meyer, Nasa's lead scientist for Mars exploration, said. "On Mars, the atmospheric pressure is so low that it's going to be boiling as it comes off. You've heard of a smoking gun. This is a squirting gun." John Murray, of the Open University, one of the lead scientists on the European Mars Express spacecraft, agreed that the new channels appear to have been formed by water. He said: "It is a really interesting and tantalising find. There is so much evidence of past water flow, but if this is right then the same is happening at the present time.

"This is one more place in which we might possibly find life. If you have microorganisms frozen in water deposits just below the surface of Mars, then yes, these could be revived.

"It's a small possibility but it is a possibility: on Earth, microbes can exist for tens of thousands of years like that and still be revived."

The images represent a fitting swansong for the Mars Global Surveyor, which fell out of contact with mission control last month after ten years in orbit around the planet.

Philip Christensen, of Arizona State University, said: "Five years ago, we were talking about water on Mars five million years ago. Today we can honestly talk about water on Mars today. That . . . has really changed how we think about Mars and how we should think about exploring Mars."