TRAIN bosses yesterday attempted to derail the first national strike in their sector in 20 years by threatening a court case over ballot “defects.”

Network Rail managers challenged the Transport Salaried Staffs Association (TSSA), whose members are due to strike on Bank Holiday Monday alongside fellow rail union RMT, to withdraw its notice of industrial action.

But unions accused the track operator of foul play, its threat coming just before conciliation talks were due to resume.