Bill Sadler’s Mark I racecar, powered by a Jowett Javelin engine. From around 1954? I'm not sure about the date. Recently featured on a well known site about classic cars, which I believe is the source of the image. I can't quote from that article as it's behind a paywall, but I have found this in another article from two years ago on a canadian website:
"Sadler wanted to build a car specifically for road racing and he wanted to most advanced technology he could find and afford. He purchased a second-hand Jowett Javelin from a used-car dealer in Toronto and drove it to his new shop at Sadler Auto Electric in Hamilton. To start the project, he removed all the parts from the Jowett - the engine, the torsion bars from the suspension and other components.
In the classic manner of the specials builder, he traced out chalk lines on the garage floor to gauge the dimensions he wanted to use. As he knew nothing about welding, he had to hire a local welder but dismissed him after learning how [to do it] himself.
"I would get a scrap piece of metal and weld it up, put it in a vice, and hit it to test the strength. Then, I took the torsion bars from the Javelin and made them transverse and adjustable. Then I took a Morris Minor rack and pinion steering box and adapted it to the front end."
He made a rudimentary body for the car and welded cycle fenders onto the chassis. Then it was off to Watkins Glen again."