In Locomotives of the GSR on pages 247,248,249 there are photos of Irish K class with the welded smoke box and the domed smoke box door. According to the potted history the MGW did a very good deal with an average purchase price per set of parts of £2,200 per engine and the Woolwich Arsenal had paid £3,375 average per boiler 3/4 yrs earlier. Cheap as chips hence the nickname Woolworths.