As far as I can tell, only two RN vessels would receive all-Danish crews. These were the minesweepers M.M.S.36 and M.M.S.83. Other ships of this class may have had Danish crews, but do not have Danish officers listed in the Navy List. Both ships were of the MMS I class of 'motor' minesweeper, so called because they used a diesel engine rather than a steam engine.

These ships were small vessels, just 119ft long, with a crew of roughly 20 men. The ships were designed for coastal minesweeping, clearing British harbours and estuaries of German mines. They were built of wood, to reduce their signature to magnetic mines, and their engines were silenced to make it harder for acoustic mines to detect them. They typically mounted three kinds of sweeps. The first was a traditional Oropesa sweep for clearing contact mines. Next was an LL sweep, which used two electric cables, one 575 yards long and one 225 yards long, to generate a magnetic field which would detonate magnetically triggered mines within the area of effect of the sweep. The SA sweep, which can be seen in this image as the large conical drum being used as a seat on the vessel to the left, was an acoustic sweep. A large noisemaker or 'acoustic hammer', was lowered from an 'A'-frame over the bows. The noise produced by this would detonate acoustic mines. Detail on the service of the two Danish ships is hard to come across. Both ships were built near Colchester in Essex, with M.M.S.36 built at the Rowhedge Ironworks boatyard, and M.M.S.83 at the Wivenhoe Shipyard, during 1941-42. They were handed over to the Danes on March 1st 1944, at the RN's base at Granton, a suburb of Edinburgh. Both ships had operated from this base earlier in the war, as part of the 104th Motor Minesweeping Flotilla. Given this, it's likely that they remained there, but I cannot confirm this. From Granton, the role of the MMSs would have been to keep the Firth of Forth clear of German mines. Particular attention would have been paid to the waters around the naval base at Rosyth and the approaches to Leith harbour. Neither ship would be sunk during the war, and both would be handed over the Danes at the end of the war, along with the corvette Geranium, eight more motor minesweepers (four of the MMS I class, and four of the larger MMS II class), and two U-class submarines.

The crews of the ships were recruited from Danish seamen who had escaped to the UK. Some would have come from the Danish merchant marine, the majority of which (60%) had fled to the UK following the German invasion of Denmark. Others might have escaped from occupied Denmark, or travelled through neutral Sweden. The formation of such 'exile' navies was common within the RN. The Free French had one of the largest, with 104 ships and small craft serving under the Cross of Lorraine during the war. The Norwegians and Poles would also receive ships from the British, or manned ships under British control. Using foreign manpower in this way had several advantages. It freed up British manpower for other duties, especially manning larger ships. It gave the exiled governments a nucleus of men experienced in modern techniques and fighting, to form the core of their post-war navies. It was good for propaganda, showing that the fight against fascism was a truly multinational affair. It also gave heart to those who remained in occupied nations, who knew that their countrymen were striving to liberate them alongside the British, Americans and Soviets.