Could be one of a vast number of trials specials of the 1950s, but I'll guess it's a very early Dellow.
Front suspension is Ford or Austin based so I'll say it's powered by a Ford Ten engine.
But now I'm sure that's wrong and it is an early version of "Buttercup" which was powered by a Standard Vanguard engine and which is held to be an inspiration for the TR2 Sportscar.