Both of those have transom hung rudders - this one has a counter and keel hung rudder.
Close, but the keel shape is different with a vertical front and the rudder is rounded rather than straight. My other thought was an Illingworth & Primrose design as they were keen on the vertical leading edge to the keel and short keel that left the rudder forward on the waterline. As Fr J Hackett says, pigs to steer - ask Chichester as the Gypsy Moth they designed had a similar underwater profileJust a vague guess:
MG 30, moulded by Somerset Plastics, home-completed?
Edit ...... the hull looks MG30, but the coachroof ..... probably not.
It might be my eyes, or the pic in the op, or the amount of weed in the op ......... bit I'm not convinced that the keel in the op has a vertical leading edge.
To me, it looks like a long clump of weed hanging down like a Spaniel's ears, giving the impression of the keel being straight at that point.The keel doesn't have a vertical leading edge. If you enlarge the photo you can see that the dark area that looks at first like a vertical front to part of the keel is actually behind the trailer/lorry carrying the boat (something on or behind the white van, perhaps?).
To me, it looks like a long clump of weed hanging down like a Spaniel's ears, giving the impression of the keel being straight at that point.
........if you look at the back of the boat the rudder is different with the lower pintle higher up so the rudder is much shorter.