Hi Graham,the reason fighter command introduced the day fighter scheme,DFS, (grey/green uppers) had nothing to do with operating over the channel as is often said but was because the earlier brown/green scheme was beginning to be a liability at the increased altitude at which the fighters were operating. The DFS was seen as a compromise giving better camouflage at altitude whilst still affording protection on the ground.The grey,though considered a compromise, is not so daft on the ground as around RAF aerodromes of the time the aprons,taxiways and revetments were almost invariably concrete.
I have seen,but can't find,a 1941 document which specifically notes that the Mosquito will be finished in the new DFS.
The aircraft of bomber command operated largely at night where aerial camouflage comprised the black lower surface,the colour of the upper surfaces being irrelevant. All cats are grey in the dark! The dark earth and dark green upper surfaces were kept as they were considered to afford better protection on the ground,no compromise required.
Whether the Mosquito had grey/green or brown/green upper surface camouflage would make no difference at night whereas during daylight,at altitude,the grey/green would be advantageous.
I did find this.
"I believe that only the first few Mosquito bombers with the short nacelles were finished in the Dark Green Dark Earth sky scheme. These aircraft were called B MkIV series 1. I haven’t got my references with me but not too many were produced before production shifted to the long nacelle version B MkIV series 2. As far as I can ascertain these aircraft were all finished in the day-fighter scheme, including sky spinners and sky fuselage band. These original machines were allocated to 2 Group Bomber Command as day Bombers.
2 Group was subsequently transferred to Fighter Command but the Mosquito Bomber squadrons transferred to 8 Group and started to fly at night. The sky bands and spinners had by this time stopped being applied to the Bombers, but they remained in the day fighter scheme with some units applying black under surfaces."
I also found this.
"In early 1942 it was realised by the Air Ministry that as the Mosquito operated in many different roles many different camouflage schemes would be applied to them on the production lines of the factories. It was mooted that all Mosquitoes, whatever their operational function, should be finished on the production lines in overall MSG. The service camouflage schemes could then be applied to the aircraft after they left the production lines either at the factory or at ASUs (Aircraft Servicing Units). The suggestion was adopted on the 12th March 1942."
As a foot note it is interesting to see how Lufwaffe camouflage reflects the same themes. Bombers and transports were always in a green scheme for ground concealment. Fighters,by late 1941were in greys for altitude protection. Fighters operating on the eastern front,operating at lower altitudes,quickly revised their schemes to green and green/brown colours like the early British schemes. At the end of the war,when the air superiority of the allies made concealment on the ground vital,the Luftwaffe fighters adopted green,grey/green,and green/brown schemes.
Cheers
Steve