This morning 90031 has arrived at his new resting place, with the assistance of DB yard mate 66065, having had the necessary wizardry from @railtec-models to create the artwork to replicate as near to what 90031 actually looks like now. Thank you Steve.
It was then the turn of Jerry @Squirrel Rail to create a significant aged look inspired by the actual example but not necessarily every blemish - the 90 in my world would likely have worked more so would be less aged now :-).