Not connected to this company but I was in hiring a small trailer today and saw they had a boat trailer in the corner.
I asked about it and he said he was one of the few places in the country doing it and people traveled miles to hire the trailer, its very popular.
It is a twin axle roller trailer with winch/post capable of handling boats to 25ft and weight to 2.5 tonnes.
Its £140 per day (discounts for longer periods). He said it has to be more costly as it seems to need continuous maintenance (bearings/brakes as it is dunked in the sea)
He can also supply a vehicle/driver as well (at extra cost)
Could be useful for those wanting to move a boat or temporarily re-locate without purchasing a trailer.
http://www.berkshiretrailerhire.co.uk/