That will be a Class 4 or OCR boat - I am betting Mr Williams raced against it!
Used to play football against Sutton Grammar!
I bought this boat, I think in 1974, having joined the Kent Boat and Ski Club, and after taking part in a few club races with moderate success, decided to try my hand at Class 4 (OCR). The attached photo was taken whilst I was applying for my RYA licence in 1976. My co-driver here is Derek Mortimer (brave man). The RYA made me change the name (no sense of humour), so I opted for 'Phantomime' in keeping with the Phantom theme as demonstrated with 'Phanta C' and 'Spectre'. In 1977 I managed 2nd place in the OCR National Championships E Class, behind Tony Sheldon in his Shakespeare.
My friend Derek, who was driving a Winner-Stapley in D class, recommended me to Doug Driver and took me down the M4 to Barry in south Wales and introduced me to their factory. Doug offered me a boat, which I readily accepted, and the finished boat was displayed on the Winner Boats' stand (upright on end) at that year's Earls Court Boat Show. It was named 'Catnic' in honour of the parent company of the manufacturer.
On the water, it was hard to keep balanced, but was very capable in the rough stuff (!) as evidenced by my lapping the entire field (all but one Dave Picton) at the Varne Trophy race in 1978.
And Yes: Barrie Williams will remember both boats I am sure.