Rail union RMT has confirmed that balloting for strike action and action short of a strike will begin this week on three main train services:Â South West Trains, Greater Anglia, First Great Western.
Ballot papers will be sent to members this week, with voting coming to a close on Thursday, July 19.
The ballots come as RMT confirms that it has now agreed reward payments on First Capital Connect, C2C, Chiltern, East Midlands Trains and East Coast to add to deals with Heathrow Express, Virgin, Network Rail, DLR and London Underground.
RMT general secretary Bob Crow said: “With deals now concluded that recognise the massive additional effort of the workforce on the vast majority of transport operators, it is a scandal that South West Trains, Greater Anglia and First Great Western have decided to try and force their staff to work longer and harder for little or nothing in return.
“We all want the Olympics to be a success, but we cannot have fairness on some train companies and a slap round the face on others.”
