A long time after the last post – but ‘All About GWR Iron Minks’, Lewis, Lloyd, Metcalf, Miller, HMRS, has multitudinous detail including ‘condemned’ dates. It’s from 1980, so presumably available secondhand or via a library if you can’t find one to borrow from local modelling friends. Not many iron minks survived into BR but there is a photo in the book of one in departmental service in BR livery. Probably most survivors spent their short time after 1948 in the last GW livery.