Yep, Jamie is correct. The two-tone grey scheme shown was used by the Banff Strike Wing, operating in Norwegian waters, and was chosen specifically for that role, in order to blend into the surroundings of the coast land and waters around Norway. The general Coastal Command scheme was an overall Ocean Grey upper surface, with a Medium Sea Grey, or Sea Grey undersurface, again for operations over water.
The subject chosen by Tamiya for their model was first 'modelled' by Airfix, in 1/72nd scale, back in the 1950's, and at one time, photographs of MM417 were almost the only ones shown of the FBVI variant. These were all taken on the same sortie, IIRC the day after the aircraft arrived on Squadron. Some of the other shots of this aircraft clearly show that the colours were Dark Green and Medium Sea Grey, where the tonal separation is more apparent. I can't remember the details of hand, but this aircraft did not stay with, or operate with the Sqaudron, moving on within a few days, possibly less, of the photo sortie.
It would seem that Tamiya have fallen into the trap of believing the captions to old published photos, which is not the first time.
This Squadron were originally a bomber squadron, formed in August 1942 with Venturas. They converted to Mosquitos a year later, and, with the other Mossie squadrons of the Group, commenced night intruder operations for the remainder of the war, although some daylight operations were undertaken. The most notable of these were the famous low-level attacks on Amiens prison, and the Gestapo Headquarters at Aarhus and Copenhagen (Shell House).
I have had the great pleasure, and honour, of meeting a number of the crews who took part in these raids, some of them well-known and highly decorated personalities, and still keep in touch with those of them who are still with us. Having spent seven years researching every possible detail concerning the aircraft and events, for a particular painting I was commissioned to produce, I can assure you that the colour scheme was as I have described, regardless of what Tamiya might have published, and, if it will help, I can provide a copy of the official Air Ministry painting grid for the Mosquito.
Cheers,
Terry.