This is kit No. 61020, probably an original release. 61021 was an early Dambusters release. The latest releases are in grey plastic and have both the early and
later bombardier's perspex, the earlier kits have only the shallower early model type. The early kit has one style of propeller, the later kit has two styles. There
were also some changes to the engine nacelles in the later kits. 61105 is a later B Mk I/III kit.