That was yesterday, so today I did a bit of internet searching and have found out that this model is called a Wavemaster, designed by Les Rowell in 1953 and was first produced by Hammersmith Model Makers, in later years circa 1960 it was produced and marketed by Yeoman Kits
An original advert from 1953, in today's money I think it works out at £3.74
In the days this photo was taken the hull would probably have been half full of RC equipment and motor
Here's my Wave master, a little broken and unloved
Who ever built her originally did do a nice job
She came with a few bits and bobs but doesn't look as if she has ever been launched
Considering the size and weight of this model this little diesel engine just doesn't appear big enough