Here is one of Searle's preparatory sketches for the central model.
'The Seven Seas', 72 x 52cm (28 3/8 x 20 1/2in) watercolour, gouache and pencil.
This drawing was also used included in the event's programme.
Here is the full programme
The Times January 1st, 1955
In the Searle Archive, Hannover I found several photographic prints showing the models Searle constructed in detail. In addition to the central construction with its King Triton & mermaid figures there are numerous other submarine creations. Evidently he also painted a back-cloth too.