It is I hope, an HVB Special, one of two GT cars built by Han van der Blij in the late 60s. This one had a BMW 1800 engine and Hewland box, the other was VW powered. Both cars were notable for being very low, as you can see in the attached photo. The VW powered car has been bought by the builder's son - that's it in the photo presumably with HVB himself. He was a prolific car builder.