This is all about Network Rail. A few years ago they updated their risk calculation algorithm for crossings risk. If a service is proposed to be changed, the risk calculation is re-run using the new formulae and if it now says the risk is too high, NR say no. As you probably know, this is one of the things that stopped the second hourly service on the Mid Cheshire Line a few years ago. NR is a nationalised company (or as Labour would put it, "in public control", ha ha) so what NR says is gospel and there is no appeal. Moreover NR has no budget for improvements, so if a crossing carries risk, and that risk prevents a service starting, that's the end of the matter. If doesn't matter if you're the Mayor of Omnium, if NR says no, you can't have what you want.