I have read somewhere that the interior of British AFVs during World War 2 was normally painted silver. If so, was this colour used throughout the war, or did it vary depending on time and location? The vehicle I am particularly interested in is the Fordson Armoured Car (a modification of the earlier Rolls Royce version).

AFAIK, WW1 vehicles were painted white inside, so the R-R's would probably have been white originally. The change happened in the 30's, I believe. Based on the Fordsons received by the RAF, these conversions were fully repainted externally so it is reasonable to suppose that they would have been repainted internally too as there was internal work done. In which case the colour should have been silver. But the base workshops in Egypt would have used what they had to hand, so white is still a possibility.