The company that owns Britain’s rail network has missed its target to cut costs over the past five years, according to preliminary estimates, fuelling calls for rail bosses to forgo their six-figure bonuses.

People familiar with early figures for the efficiency target say Network Rail cut the cost for each unit of work by 27 per cent, instead of the 31 per cent it was set by regulators for the 2004-09 period, which ended on March 31. The estimates have been drawn up by the company and its regulator.