Well they look like well built tubs to me , worth restoring and driving tax free
Yes, I think you are right there; they were well built for their time. The engines could easily break, and the bodywork would eventually rust badly, with no rustproofing as I am aware. But that was typical of all cars built in the 1950s and 1960s.
They were heavy beasts of thick steel, and that is why a number still survive. If I remember correctly from that time it was the engine that always spelt the end for those cars. I know my father in law preferred to buy old Austin Westminster's, Humber Super Snipes, and some other larger 1950s, early 1960 cars. They all died due to engine problems (big ends gone, cylinder head cracking, carburetters wearing out, pistons burning through). I know the Humber Super Snip (what a lovely heavy beast for me to drive, double-de-clutching with no power steering for three tons of car) I 'broke' when a valve rocker snapped. There were also a knocking big end, so my father in law decided to scrape it as it was only worth £50!