Decisions by the leadership during the two-month campaign of industrial action seem to have the backing of most signal workers. In an 80 per cent turnout - virtually unheard of in postal ballots - RMT members voted by 4-1 to take strike action and few have registered their backing for the management offer.
There is little doubt that Jimmy Knapp, leader of the RMT, would be 'reined in' by his executive if he proposed a 'sell-out', but there is little sign that he wants to.
Mr Knapp's aides say even if some executive members wanted to accept the deal offered by Railtrack, they would have difficulty selling it to members.
The executive is generally regarded to be split 13 to 8 in favour of left wingers. But the opinions of the most radical faction range between far-left ideology and 'soft-left' support for John Prescott, the deputy leader of the Labour Party.
Two of the most left-wing executive members represent London Underground. One is Bob Crow, a 32-year-old self-proclaimed Marxist-Leninist and a supporter of the 'Stalinist' Communist Party of Britain. The other is Patrick Sikorski who, as a member of the tiny Trotskyist group Socialist Outlook, is several points to the left of Mr Crow. Mr Sikorski, a 42-year-old tube guard with a university education, was dismissed by London Underground last year after allegedly threatening a manager, but reinstated after colleagues staged a 24-hour walkout.
One of ambitions of the two is to co-ordinate action between Railtrack signal workers and their colleagues on the London Underground. So far that strategy has failed.
Railtrack, at one stage during the last round of negotiations at Acas, said it detected the influence of the left preventing a settlement. Leading right-wing trade unionists in the industry, however, believe there is genuine support among RMT members for the dispute and point out that while the union's executive is still demonstrably left wing, it is more moderate than it has been for some years.