A new “legal right” to maximum waiting times for NHS treatment, part of a Labour attempt to protect its national health commitments against an incoming Conservative government, turned out on Tuesday to be less robust than its announcement suggested.

Gordon Brown, the prime minister, and Andy Burnham, the health secretary, said patients would have the right to go to another provider, public or private, if the NHS failed to provide their routine treatment within 18 weeks or an initial specialist cancer consultation within two – the current government targets.