Bigger than a Buckingham eh?
Vickers can offer an improved Wellington;
Wellington B.IX
Dimensions; 86.2/ 60.10/ 17.5/ 840 sq ft; 2x Bristol Hercules 1,770hp VIII radials; max speed 250mph; range 1,750 miles with 4,500lbs bombs or 2x 21in torpedoes and service ceiling 19,000ft.
Armament: Up to 4,500lbs of bombs, nose turret with 2x MGs, dorsal turret with 2x MGs and tail turret with 4x MGs. Provision for ASV radar for maritime role.
Avro offers the 683 Lancaster
Dimensions; 102/ 69.6/ 20/ 1,297 sq ft; 4x 1,650hp Rolls-Royce Merlin VII; max speed 287mph at 11,500ft; cruising speed 210mph at 20,000ft; range 2,530 miles with 7,000lb bombload and service ceiling 24,500ft.
Armament: Up to 14,000lbs of bombs, nose turret with 2x MGs, dorsal turret with 2x MGs and tail turret with 4x MGs.
Avro is also studying an improved Lancaster with new wing and Rolls-Royce Griffon engines.
Unsure on exact specs yet but certainly based on the OTL Lincoln with perhaps a tad more speed. Would not be ready until 1943/44.
Armament nose and tail turrets with 2x 0.5in MGs and dorsal turret with 2x 20mm cannon.