Looks like the final frame assembly operation. The T handles are on a jig to position the oil tank and air filter mountings on the rear chainstays, ready for a quick dab of braze.
Before the advent of flip front goggles it was always a bit long winded putting down the torch or rod to lift the goggles and inspect the job. A single eye shield makes the job quicker and more productive. Back in the old days of time study and measured daywork, it was a battle between them that measured and them that did. You can bet the job was timed with fine attention to detail by the man with the torch, conventional goggles, stretch the time a bit. Then when under starters orders, out came the single lens and he knocked them out like machine gun bullets. Oh the joy of piecework!
My guess is that they are engineering students from the nearby University of Birmingham on a works visit, along with one of their tutors. All a bit dangerous, the fine tweeds could be ruined by a wayward spark, and it is interesting to see what workers wore in those 1950's days before the introduction of any workwear and the styled corporate workwear we have now. Mostly the demob suit in the case of dockers, brickies and guys digging holes by pick and shovel.
Swarfy
