Services on some of the country's busiest rail routes were being disrupted today because of a strike by train drivers in support of a sacked colleague.
Members of the Rail Maritime and Transport workers union based at South West Trains' London Waterloo depot walked out for 24 hours, with the threat of the action escalating.
The union plans to ballot all its members on SWT in protest at the dismissal of Sarah Friday.
She claimed she was sacked because of her union activities but the company strongly deny this and maintain she was in serious breach of her contract.
Mainline services in to and out of Waterloo were not expected to be hit but disruption was predicted on suburban routes in south London and Surrey.
SWT said it had offered to go to arbitration to settle the dispute but claimed the union had rejected the idea.
The company said Ms Friday had now lost an internal hearing and been told at an interim tribunal that she was unlikely to win her case.
Managing director Graham Eccles said: "We have bent over backwards to prove that the dismissal was not unfair."
Vernon Hince, the union's assistant general secretary, said: "This is a clear case of victimisation of a union health and safety rep and we are now going to extend our action."
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies