Milton Keynes doesn't need any more VT services stopping in the morning peaks. Not sure about evenings however.
Part of the reason there is overcrowding is because VT stop some services there. Because they're quicker than the LM ones, MKC passengers choose the VT services rather than the LM ones.
The 0714 departure can get dangerously overcrowded if a 390/0 turns up which has frequently been the case recently. A 390/1 can cope, but I've been on some /0 services where there have been announcements requesting pax to vacate some coaches as they have been overloaded and the train won't move.
There's the 0717 LM service which stops at Leighton Buzzard only which takes 8 minutes longer to get to Euston and that will be sat on the slow line platforms with loads of space yet everyone piles onto the VT service.
People take umbridge with MKC passengers as many are completely uncivilised. I travel on VT services which pick up at Stafford, Lichfield Trent Valley, Tamworth and Rugby. Commuters can board the train at these stations in a civilised manner, take notice of the quiet zone, don't fight for seats and don't spend the journey time into Euston shouting at each other or down their mobiles. MKC passengers however seem incapable of this on the 0714.
Surely a better solution would be to make all LM services 3 units and extend the Tring services to MKC?