The New York disaster is raising serious questions over the future of building and working in high-rise towers in financial centres, particularly those at concentrated sites such as London's Canary Wharf.

A leading security expert, Nigel Churton, chief executive of Control Risks, said: 'Do you really want to put up a building with your name Jones Inc all over it and pour all your people into it?' Churton was referring to the trend to one-site consolidation among financial firms and legal firms. 'We have seen entire teams, even entire businesses, wiped out in New York, yet all the actuaries would have told you you couldn't possibly lose the two World Trade Center towers.'