Demand for survival kits for commuters has soared since the July 7 attacks.
The kit, which fits in a back-pack or handbag, contains a particle mask to filter out dust, a torch, whistle, water and antiseptic wipes.
Simon Johnson, managing director of SurvivalBox, said sales increased 150 per cent in the weeks after the first wave of bombings.
Mr Johnson, a former investment banker who set up SurvivalBox after the September 11 attacks in the US, said such products were designed to provide reassurance. The company sells the packs for £19.99 over the internet.
He said: “There is not much you can do if a bomb goes off in your carriage. But an emergency kit at least helps you to get out of the Underground if you happen to be in the carriage next door. It is a psychological thing.”
Companies and households have also stocked up on larger emergency sets, which contain foil blankets, ropes, crowbars and emergency food provisions.
Mr Johnson said 80 per cent of his corporate customers were London-based banks or insurance companies, but there had also been an increase in calls from government departments and foreign embassies.
Inquiries for satellite telephones have also soared, particularly from financial institutions anxious to guarantee communications between key staff. Mobile phone networks and landline services were temporarily disrupted on July 7, partly because of congestion but also because capacity was set aside for the emergency services. Satellite phones were unaffected.
Satellite phones are seen as a communications means of last resort. Most service providers contacted by the Financial Times had seen a surge in inquiries, but many said it was too early for concrete sales data. Ross MacLeod, marketing manager of Cellhire, said: “We have had a surge in interest, especially from City companies.”
The phones, which start from about £500 plus line rental, are unlikely to be affected by network congestion. However, they are not always practical in built-up areas because they needline-of-sight contact with the satellite.
Companies are also touting international SIM cards to circumvent network congestion. While domestic SIM cards are limited to one network, an international card can roam into any network available in the UK.