The 53xx's sent to France were all built using secondhand boilers. I haven't looked more broadly over the rest of class, so this may have been due to the exigencies of war. I would expect though that once withdrawal of earlier Churchward engines began in the 30's, smaller parts were more widely recycled for new construction. It's a shame Swindon didn't include the date when they stamped a new number in! I think 'recreation' is a suitably ambiguous term.