In the end I decided not to purchase a charging point from Chargemaster. The information they gave me on several different telephone calls seemed to be so changeable and their pricing structure seems unusually opaque. Having arrived at what seemed to be the correct price and applied for the OLEV grant I was then told the work would be more extensive, needing an external contractor at extra expense. When I queried it they seemed unsure whether this really was necessary, but in the end assured me it was. This may be correct but by this time I had lost confidence in them.