The Boston Mk III was originally named DB-7B. It had changed electrical and hydraulic systems, and instrumentation which conformed to RAF requirements and layouts. These were also designated Boston MK III and carried four 7.7mm(0.303 in) guns in the nose, two on a high speed mounting in the aft cockpit, and a seventh gun firing through a ventral tunnel, plus a bomb load of up to 2,000 lb.These Boston MK IIIís were used extensively by squadrons of No.2 Group, and served also in North Africa from early 1942 replacing Britol Blenheims.