According to Michael Bowyer's "Fighting Colours", the black/white started be phased out for fighters by end-May 40. However, he also notes that battle-damaged a/c could come back from repair still wearing B/W. It was apparently Feb 41 when the Black was to be removed [presumably at your leisure, there's a War on!!] except for Westland Whirlwinds. "Duck Egg" then took over for general use in UK.
If that photo is an OCU, anything could probably happen until someone had time/effort/equipment to repaint things.