Forte, Britain's biggest hotelier, is likely to suffer particularly if nervous tourists decide to stay away from the capital. It has a strong London presence with prestigious hotels like the Waldorf, Grosvenor House and Hyde Park Hotel which are particularly attractive to Americans. This is also the key period for booking rooms for the summertime. However, US tourists have proved very jittery about coming to Europe after terrorist incidents in previous years.
BAA, the former British Airports Authority, runs Heathrow, Gatwick, Stansted and four other airports around the country. It collects a fee as every plane lands on its tarmac, as well as a slice of the lucrative traffic in duty-free goods and bureaux de change.
Shares in Forte fell 9p to 255p on Friday as fears spread throughout the investment community. BAA dipped 10p to 994p as analysts calculated how much the company would have to add to its pounds 100m-a-year security bill.
The British Tourist Authority has also expressed concern about the possible impact. On Friday it contacted its offices in mainland Europe, the US and Far East to monitor sentiment. 'There was quite a lot of media coverage but they haven't yet had any calls from worried consumers or trade organisations,' said a spokeswoman.
However, the BTA is readying itself for further 'spectaculars' in line with Republican threats. Any attacks may have a dramatic impact on one of Britain's biggest industries.