I wonder if it might be a Calypso, which was designed by David Cannell (of Samphire 'fame'), and built by North Sea Craft of Norwich/Wroxham.
The pic on the trailer looks consistent with the Calypso's retracting twin keels, and the look of the front of the boat is consistent with the only pic I've ever found of one - there are few Calypsos about it seems. I guess they were rather expensive to build compared to the competition, and may have come out just as the British boat building industry was taking a pasting.
If it turns out to be a Calypso, I'd be grateful if you'd PM me any more pics you have.
One source of info might be whoever the boat was registered with (prominent number on side of boat).