Transport For London spent £8 million last year paying staff for time off to attend official union duties.
The cost increased from £4.4 million during the final year of Boris Johnson’s mayoralty to £7.9 million in 2018-19.
TfL allows union representatives paid time off for union duties, so-called “facility time”, and meeting these costs represents 0.4 per cent of its total wage bill.
The number of staff spending more than half their time on union activities rose from 48 in 2015/16 to 148 last year.
Keith Prince, London Assembly shadow transport spokesman, said: “Londoners want the Mayor to be concentrating on improving our creaking transport network, not splashing out on trade union perks.”
The Mayor responded by saying under his tenure there had been a 74 per cent drop in the number of days lost to strike action and it was no good “angrily shouting” at staff from the sidelines.
The number of representatives for TfL’s 27,500 employees is in line with legislation and agreements with the trade unions.
