I have had some experience with both Sidchrome and Snap On tools whilst servicing RAAF aircraft many years ago, and had a Sidchrome toolchest myself with a combination of SAE (A/F) and Whitworth sockets and spanners, which, incidentally, was stolen from a shed I had it stored in during a move.

I found the Snap On tools very good quality; in fact excellent....but Sidchrome was also good quality in those days (1967) and had a life-time guarantee. the catch-cry was...You canna hand a man a grander spanner!