Who's sitting next to you?

"Looking after you in the economy cabin will be Penny, Sarah and Kate. The gentleman in seat 27D counting his Air Miles is Jonathan, your sky marshal. Today his weapon of choice is a low-velocity revolver loaded with fragmentation bullets." Unlikely? Perhaps, but such an announcement is the logical conclusion of the preposterous sequence of events that began last Sunday.

In case you have been incommunicado at Heathrow waiting in vain for BA flight 223 to Washington, or sunning yourself on a far-off beach, here is what happened that afternoon. The Home Secretary, David Blunkett, and the Transport Secretary, Alistair Darling, issued a press release announcing that armed "sky marshals" will travel incognito aboard UK aircraft. The following morning, Mr Darling told listeners on the Today programme that the sky marshal would travel incognito, but that pilots would be tipped off if one (or more) was on board.

According to the British Airline Pilots' Association (Balpa), this was the first that they had heard about it. Bookings for Air India from Heathrow to New York JFK and Air New Zealand to Los Angeles soared among travellers who prefer to fly the Atlantic on a "neutral", unarmed airline. By Monday evening, Tom Ridge, the US Secretary for Homeland Security, closed this loophole by insisting all airlines flying to, from or over America, should carry a rear gunner on flights the authorities deem risky.

A travel company in Addis Ababa, Eastern Travel & Tours Agency, has the catchy slogan "For Those Who Appreciate Mystery". The same motto now applies to people flying to America, who henceforth can never be sure whether the passenger next door is a member of the Mile High Rifle Club - at least until the firing starts.

What is a captain to do? Imagine yourself as the senior pilot on a flight to New York, being told "A sky marshal will be aboard your aircraft". One rational reaction would be to deem the plane too risky to fly. But to prolong employment prospects, a more realistic response is to find out where the marksman is sitting and pass this information on to the purser in charge of the passenger cabin - in case things turn nasty or a villain in another seat impersonates a sky marshal.

In turn, the senior flight attendant would want every other member of cabin crew to know. And so that the people who keep the whole show on the road, i.e. us fare-paying passengers, are not kept completely in the dark, some crews may choose to announce the presence, and seat number, of the sky marshal.

In any event, he or she should be easy to spot; the one declining all offers of drinks, trying not to fall sleep, and watching the inflight dramas rather than the films on screen.

The American authorities, still raw from the attack of 11 September 2001, are at liberty to make any stipulations they wish about flights going to, from or over the US - just as travellers are free to decide whether to travel on a plane that may contain at least one armed passenger.

If, as some security sources suggest, there would perhaps be as many as seven sky marshals on a single flight, quite soon the number of armed guards will exceed the number of ordinary passengers. While this will do wonders for security, it will not help airlines' profitability - or the sky marshals' health.

Flying is so incredibly safe that the greatest risk to human life from the new ruling is of deep vein thrombosis (DVT) afflicting the marksmen. Their principle activity is to sit still on aeroplanes. Cabin crew get plenty of exercise while on duty. Pilots do not have much room, or time, to move - but the working time of pilots is limited to an average of under three hours a day. The 21st-century shotgun riders could end up spending day after day, and night after night, static in economy class and at risk of fatal blood clots.

Thirty-five years ago, when you could fly to the American capital without an armed guard and a fighter escort, the top tune was "What a Wonderful World"; today, it is "Mad World".

HAPPIER MATTERS: 2004 could be the best year yet for travellers. The dwindling dollar is driving the cost of air travel down, and the range of destinations will expand rapidly - particularly to Poland, the Baltic republics, Hungary and Slovenia once they accede to European Union membership in May. The government of Latvia is cutting airport taxes in the capital, Riga, to make it the no-frills hub of the Baltics. Expect a non-stop flight from Luton or Stansted to be launched by May, providing a fast link to the sea that, if you believe the global warming doomsayers, will soon enjoy a Mediterranean climate.

In the real Med, Corsica, Sardinia and Sicily will become the islands of choice thanks to new flight links. British Airways plans a once-weekly flight from Gatwick to Bastia in northern Corsica from May. But I predict that by the summer BA and other airlines will have laid on more capacity; even during BA's current seat sale, the lowest fare I have found for the new route is £155 return, almost as much as a transatlantic flight.

North America will tempt millions of us across the Atlantic, not least thanks to those entertaining cheap fares; yesterday I was quoted £200 return for a Heathrow-Montreal-Boston combination. Once there, travellers may emulate those heady days early in 1992, when the pound bought two dollars.

Going east, long-haul air services will increase and fares will fall still further, especially to the Gulf, Asia and Australasia. The best value will be found in countries whose currencies are tied to the US dollar, from Honduras to Hong Kong.

On the high seas, competition across the Bay of Biscay will increase sharply. Brittany Ferries is launching a new higher-speed ship on its existing service from Plymouth to Santander, designed to increase the edge on P&O's Portsmouth-Bilbao link. The new ship is scheduled to take 19 hours, saving five hours on the present crossing time. Expect lower fares.

Moving upmarket, the launch of the Queen Mary II will stimulate yet more growth in cruising, even though she epitomises all the design values of the Travelodge on the M4 outside Reading. Cruise bargains will abound as the dollar slumps and more new ships compete for custom.

Britain's travel industry is finally waking up. In the past few months, train, bus and hotel companies have introduced the pricing techniques employed so successfully by low-cost airlines: tempting travellers with very low prices to fill off-peak capacity, and at other times increasing rates in line with demand. A promotion launched at midnight by Travelodge, offering online rooms on the M4 and elsewhere for as little as £5 per night, undercuts even the youth hostel.

National Express (see "Bargain of the Week", below) has capped its highest advance-purchase one-way fare at £9 for the first two months of the year, and is also quietly selling long-distance bus tickets for as little as £1.

Stelios Haji-Ioannou, the founder of easyJet, may at last launch his promised easyBus and easyDorm operations, and force prices for coach seats and hotel beds down still further. And you will see neither armed guards nor F16 fighter escorts on the easyBus.

British Airways (0870 850 9 850, www.ba.com); Brittany Ferries (08705 360 360, www.brittanyferries.co.uk); National Express (08705 80 80 80, www.national-express.com); P&O Ferries (0870 520 2020, www.poferries.com); the Travelodge £5 per room per night promotion is available only at www.travelodge.co.uk/fiverfrenzy