A unique pair of prototype DEMU's built in the 80's, one 4 coaches long powered by a Paxman engine, the other 3 coaches long and powered by an MTU. Built in a way not unlike the Southern region Thumpers, with half of one driving coach taken up by the engine. Both did not last long in service. One has been completely scrapped, whilst the unpowered driving coach of one has survived as the Class 316/457 prototype. https://en.wikipedia.org/wiki/British_Rail_Class_210
I remember reading about this one not long ago, definitely not a bad idea, the only problem is where the sounds could be sourced from, since there is no surviving example of the engine, unless there's another MU that uses the same model? Here's what the 210 looks nice now, after having been converted to electric operation for the 316/457.
Sorry to bump the thread, forgot to read back on this. The four coach unit had a Paxman engine that sounded a lot like a Valenta, though without the scream. I can see Valenta sounds being used at least temporarily on this unit. There are real world plans to reunite the 210 coaches and convert a 455 driving trailer into a motor coach using a very similar engine, but that won't happen anytime soon.
