During World War Two, the R.A.F. evolved its own private navy comprising nearly a thousand vessels. Largely consisting of small search and rescue vessels, such as the model offered, they played a vital supporting rôle to the air defence of Great Britain and it is surprising that relatively few models are known. It is presumed this example is the result of a professional commission because of the overall high standard of workmanship. The 'MU' referred to in the engraved details refers to Maintenance Unit.