Amid strenuous denials from union leaders, management estimated that nearly 20 per cent of the signal box staff rostered to work crossed picket lines during the 13th strike, compared with 16.5 per cent last week.
But a spokeswoman for Railtrack was cautious about predicting a management breakthrough in what is now the most serious industrial action in the public sector since the miners' strike in 1985.
'We are not talking about the strike crumbling, but we are saying there is a significant drift back to work,' she said. Even on Railtrack's figures, however, the dispute would have several months to run unless there were to be a sudden surge of dissaffection with the strikes.
The union last night conceded that 'a dozen or more' of its members might have decided to defy the stoppage for the first time, but derided Railtrack's figure, which would mean nearly 90 new strike breakers.
The RMT transport union argued that the proportion of routes in operation was nearer 30 per cent. Management said even more trains would be provided today before the strike ends at lunchtime.
With little prospect of negotiations, the dispute has descended into a propaganda war with both sides attempting to undermine each other's morale.
British Rail said it provided a number of 'flagship' routes yesterday for the first time on a strike day including London-Edinburgh, London-Sheffield and London-Leeds. InterCity ran an almost full service in some regions, the Chiltern line was near normal, 90 per cent of trains ran in the Thames region and 60 per cent ran on Merseyrail.
However, many services ground to a halt shortly after midday and emergency timetables were again in operation, with services often ending at 6pm last night.
Jimmy Knapp, general secretary of the RMT, said Railtrack was desperately trying to 'talk up' management's position. He said management had become 'a little cleverer and more ruthless' in the way it deployed limited resources on strike days. Supervisors and managers were being brought in on their days off. 'It is not a question of our people going back to work. We are calculatng the numbers returning in ones and twos here and there,' Mr Knapp said.
Despite denials by senior Westminster sources, Mr Knapp believes management is trying to 'soften up' his members before offering them individual deals. 'They are in a dilemma. They don't want to pitch the offer too high because the Government would ask questions, but they don't want to pitch it too low and be left with no shot in their locker.'
Andrew Rowe, MP for Mid Kent, said that if the strike escalated so that commuters became increasingly inconvenienced, while the impact on pay was 'minimised by skilful choice of hours of striking', then 'the employers should take a much tougher line.
'I wonder whether they shoudn't actually suggest that if people continue to refuse to provide a service to the travelling public, they should face dismissal.'