Around 8,700 staff will now have their scheme membership backdated to their first day of employment, with missing employers’ contributions paid up in full, and missing employee contributions, averaging £90, deducted over the appropriate number of pay periods.

The deal comes some two years after an RMT rep noticed that many trainees, probationers and workers initially employed on fixed contracts but subsequently taken on permanently had not been offered their right to be in the pension scheme from their first day of employment.

In detailed discussions with TfL and LUL it emerged that nearly 5,700 former trainees and probationers had been kept out of the fund for up to 147 days, while some 3,000 erstwhile fixed-term workers had lost between 150 and 1,000 days of fund membership.

“This is excellent news which will mean bigger pension entitlements for thousands of Tube workers,” RMT general secretary Bob Crow said today.

“This was a simple blunder, but had it not been for the sharp eyes of RMT reps it might have gone unnoticed and deprived many families of their full pension entitlements.

“It has taken us a long time to get there, but TfL and LUL have shown good faith in negotiating this settlement, and no-one should now lose out.

“Former Metronet workers who were forced into inferior pension arrangements thanks to privatisation are now also to be given their right to join the final-salary scheme that all Tube workers should be in,” Bob Crow said.