Following on from PDR's mention of RFC/RAF technical trades my grandfather was a White Metal tradesman but rather ran just creating engine bearings his skill in metal meant he specialised in the one off fittings created in the factories without drawings or measurements passed on to purchasers. In one of the war museums you can see the tradesmans' wooden caravan where they did all the metalwork.
As a reservist he was called up for WW2, escaped from France in the back of a Fairey Battle and then spent the rest of the war on civvy hours doing the tear downs and analysis of failed radial engines sent to RAF Sealand as a central analysis point.
Rather good with his hands and spent the years between the wars doing the stained glass in St Asaph cathedral and then called in to do the ceramic cladding of the original Mersey tunnel.
Rob