Graeme,
The interiors of D1013 and D1062 are painted a colour called "County Cream" which is a reasonable match for the cream that BR used in maroon days. I think light grey was quite common in BR Blue days but I have seen photos of blue 1000s with a cream cab interior in the early 70's - D1019 after it's last overhaul in 1972 for example.
Just to muddy the waters a little, when the WLA were repainting the cabs of D1062, on scraping back the paint they found maroon up to side window level and cream above that.
If you compare early photos of Swindon and Crewe 1000s you will notice that Crewe examples have electrical conduit on the cab bulkhead painted light orange, but Swindon locos do not. Photos of 1000s in the very early maroon days also seem to show the whole interior side of the cab door painted maroon or a dark colour.
By BR blue days, Swindon painted everything light grey and didn't bother with colour coding pipework in the cab.
But as a generalisation, cream for Maroon/Green days and light grey for BR Blue days.
Roger