I managed to identify the last of the 22 Giesl Austerities: it's Hunslet 3196/1944, or No. 53 at Ashington. I updated the first post accordingly.
As a result, I can narrow the search down to three+1 networks (Baddesley/Kingsbury, Wemyss, Whittle/Ashington/Backworth; and Comrie where Hunslet...