It's Tim Dutton's first car, the Mantis, built in 1969.
It was based on a Lotus 7 chassis and originally had a Coventry Climax engine, which was replaced before he sold it by a Sunbeam Alpine motor. Noboby want to buy any so he moved on to making a Lotus 7 style car; the rest, as they say, is history...
Your image seems to have got itself reversed. It should look like this, below, with another picture I found: