A new Millennial railcard promised by Phillip Hammond in the last Budget may never fully launch, as a trial starting on Tuesday is expected to cause a Glastonbury-style scramble for tickets.

Despite 4.5 million 26 to 30 year-olds eligible for the railcards which entitle them to a third off train travel, rail companies have agreed to sell just 10,000 as part of an initial "national trial".

They go on sale on Tuesday morning and will be bought on a first-come first served basis.

A spokesman for the Rail Delivery Group, which represents train firms and issues railcards, has refused to confirm that the railcards will fully launch following the trial, leaving doubts over whether it could be kicked into the long grass.

He claimed that firms needed to conduct a national trial to ensure they were "right for customers".

Campaigners have warned that a failure to launch the railcards in full would send a message to young people that the Government "simply doesn't care" about them.