A cohort of US financial firms are being accused of using speed – an advantage of just a few thousandths of a second – to fleece big money rivals and by extension ordinary savers and investors.

The allegations made in Flash Boys: Cracking the Money Code by Michael Lewis have prompted the US Justice Department to say it is probing high-speed trading for possible insider trading violations. The FBI and US financial watchdogs are also investigating the industry.

The book focuses on Wall Street share trading, but one City insider has commented: ‘The same players are in the UK and Europe – if it’s happening in America, it’s happening here too.’