Park and Ride schemes are a bit of a curate's egg in a number of ways.
Firstly, there is the argument that you are merely fuelling car use and making it easier in some respects rather than trying to get people to not drive at all. Think there has been research on that but some years ago.
More importantly, there is a bit of a disconnect now in park and ride across the UK. Some places are still very pro, and see it as a key way of meeting their NO2 and clean air targets such as Bath and York. However, in some places you are seeing a mix of collapsing high street footfall (through internet shopping) leading to many towns now promoting cheap (or free) parking in town. That really is against the idea of P&R and supresses demand.
Moreover, the dead hand of austerity means that a number of local authorities have withdrawn or reduced funding. Swindon has closed one site (though I think it was poorly used IIRC) and Worcester has abandoned it altogether. In other instances, you're seeing the dedicated services being axed and replaced by diversions of existing bus services - Salisbury is a good example as is Weymouth and indeed, Swansea have just announced something similar. In some places, there has been a transition to fully commercial operation though (think Plymouth is, and Taunton though with a pump priming grant to transition it from supported to commercial).
