According to the "Combat Squadrons of The Air Force, World War II", published by the Department of the Air Force, Office of Air Force History in 1982, the 857th flew Carpetbagging missions between the period 10th August - 16th September 1944 and the 858th flew them between the same dates plus 12th March to 25th April 1945.
The record notes that the 859th also flew Carpetbagging missions during the same 1944 period and also 31st December 1944 to the end of the war in May 1945.
So photo late summer 1944?
The 857th flew the B24, B17, A26, P51 and C47.
The 858th flew the B24, A26, C47 and interestingly the Mosquito in 1945
The 859th flew a proper medley including L49, O-46, O-47, B18, B24, B17, B25 and C47
857th UK bases included North Pickenham, Harrington, Bassingbourne and Alconbury
858th UK bases included North Pickenham, Cheddington and Harrington
859th Uk bases included North Pickenham and Harrington