Once I know a GWR engine went into GWR Wartime Black, then I make it an aim to add that engine into the collection as I find it to be a unusual livery which has very little to go by unless you documentation or photographs to show an engine in the livery.
So far a Hall, 2251 and 28xx have gone under the repaint scheme into War Black. Future projects include a Dean Goods, 38xx, Grange and ROD. Also looking at a Castle and King but of course in GWR green with cab shielding
Garethp8873.