When his Banshee was offered for sale after 52 years of his ownership (here), he'd typed out the specification in much technical detail, but not forgetting to add some whit: "Banshee was born out of the need to have something to compete in the the (then) Sports Car club's racing class that was clearly beyond the capabilities of my well rallied and raced, mildly tuned 850 Mini in the early 1960’s."
He made no secret of his inspirations, too: "Inspired by a road report in CCC of the Unipower GT, I set about 'borrowing' some ideas from that source and a terrific book called 'High Speed Low Cost' by Allan Staniforth. (...) A visit to the then Cox GTM factory in Manchester cured my problem with the acquisition of a set of their prefabricated lower wishbones, with built in negative camber, that effectively lock the uprights in the right direction."
He sold his Mk3 Mini Marcos before as he'd sold his 998 Mk1 Cooper, but kept Banshee until days before his death: "Considering the old girl was designed over 50 years ago with construction having taken about 12 years (I was transferred around the country a lot in my airline sales job) and first being road registered in 1980 in Pinetown, she continues to provide a lot of fun for my two sons now in their 40’s who were just a twinkle in my eye when Banshee was born. I quite enjoy her company too!"
All the best wishes and condoleances to Tertius' family and friends. He will be much missed in the Mini (derivatives) scene also.
Tertius van Zyl with Banshee - the Unipower GT inspired car that he built as a youngster
Picture via Gary Johnson-Barker