The experience of the commuter who fell asleep on a train and found himself locked in for the night at Brighton station (The Argus, April 3) asks questions not only about Thameslink's procedures but about the safety of these new trains.

In an emergency, such as a derailment, passengers on slam-door trains had multiple ways of escape.

But once the power is cut off, how exactly does one escape from a train with electric doors?

According to Mr Roberts' account of his ordeal, even operating the emergency door release button is useless in such circumstances.

Also, these new trains have far fewer escape apertures to start with.

-Charles Newman, Manchester Street, Brighton