We hired a big one about fifteen years ago from a place in Derby, I can't remember the name, sorry.
However, it was a wonderful family holiday - probably the best we ever had. We toured around England for two weeks with four small children. Most of the time we were just visiting scattered friends and relatives, but some days in the New Forest and also in London were very special.
The cost seems astronomic, but not when you calculate the per-person-per-day rate.