London Underground has sought bids for a £1bn resignalling programme on lines covering 40 per cent of its network, as part of a key programme of work intended to boost capacity by nearly 50 per cent.

Tim O’Toole, LU’s former managing director, expressed concern when he left London Underground at the end of April that work on the sub-surface lines – which run in wider, shallower tunnels – could be postponed because of the economic slowdown. A tender detailing the work involved had been meant to be issued in April.