The incorrect back-to-back gauge went back to Scalefour Stores this morning.
Meanwhile, three useful books published by the Belfast & County Down Railway Museum Trust turned up today, courtesy of Cuan Publications:
Each volume is limited to 550 copies; not sure how many of each class the Trust has sold so far, but I'd say you should get them whilst you have the chance.
Having read Volume 6, I am now having very impure thoughts about creating a "WT"-class 2-6-4T.