I think it can help in the very early stages, and with ds1 it definitely did for the first hour, because he was OP and it did help a bit with the backache (but only from about 0-2 cm.). After that, (I was on the induction ward, with a student mw looking after me), I buzzed her, said 'I would like to go to the delivery suite now for better pain relief', she said 'oh no, you're MUCH better here, we give you much more 1:1 until you really need to go to delivery'. I said 'but I really want to go now', she said 'but you're not in labour' I said 'yes I am, I was before I got here, you've speeded it up with induction' (long story), she said 'oh no, you'd be in MUCH more pain if you were in labour' I said 'but I am in LOTS of pain', she said 'oh no you're not....'
etc
She then said 'Well I'll phone them'....phoned them, then said 'they're VERY busy down there, I think you're MUCH better off staying here'. But we'll just see how you're getting on......'
1 examination later we were on a wheelchair SPRINTING to delivery, as I was about 8cm.
Not in labour????
It was then some time, because ds1 was OP, I had an epidural, because I was totally shocked at how badly it hurt (having not been allowed anything except paracetamol up till 8cm), ds1 got into distress and we nearly had a CS, but fortunately I managed to push him out).
My next 3 were born at home with no pain relief at all.