Motor Gun Boats

The Royal Navy’s Motor Gun Boat (MGB) emerged in response to the threat posed by German S-boats. Operating from their bases on the Dutch, Belgian and French coasts, S-boats posed a significant threat to British coastal convoys for which the Royal Navy were not prepared. Sufficient number of warships were not available to adequately protect every convoy and, although equivalent Royal Navy motor boats were becoming available in greater numbers, they were ill equipped to engage the German boats. Motor Torpedo Boats (MTBs) lacked sufficient firepower and their torpedoes were useless against fast moving and shallow hull boats. Motor Anti-Submarine Boats (MA/SBs) were similarly under equipped and too underpowered to counter this threat. What was required was a boat of comparable speed to the MTB, but with increased firepower that would allow them to directly engage the S-boats.

Around the country, small boat manufacturers were producing a variety of MTBs, both for the Royal Navy and other countries. Those being built for foreign navies were hastily requisitioned by the Admiralty and the orders amended to MA/SBs. The first MGBs evolved from these MA/SBs, which were re-engined and given heavier weaponry (largely using whatever was available). MA/SBs still under construction (principally at British Power Boats’ yard at Hythe) were completed as gunboats and from January 1941 onwards, were formally commissioned as MGBs. British Power Boat produced a design for a purpose built MGB in February 1942 and existing Admiralty orders for MA/SBs were changed to the new design. At the same time, both Elco and Higgins boats became available from the US under Lend/Lease and were hurriedly rushed into service.

These early boats were all hard chine semi planing hulls of between 63ft and 71ft. The Admiralty desire for a larger boat capable of engaging S-boats led to the design of an 115ft gunboat that would ultimately be built by Fairmile as the Fairmile D, or Dog Boat. As a stopgap solution, in 1940 Fairmile A designs were adapted to produce a more powerful form of motor launch, which would be classified as the Fairmile C. These ‘long’ boats began to enter service in 1941, followed by the first truly purpose built MGBs, the 71ft 6in Mk V ‘short’ boats built by British Power Boat in the spring of 1942. The Fairmile Ds began to enter service later that year.

Early MGBs kept the same pennant number as their MA/SB identity and, as MA/SB’s 1 to 5 and 22 to 39 were never recommissioned, these numbers were never used by MGBs. Instead, the pennant list starts at number 6, the first 70ft MA/SB. Because pennant numbers were assigned at the point of order (or the point at which boats under construction were requisitioned) and not at the point of commissioning, many of the MGBs entered service out of numerical order. As a result, there is no consistent pattern to the allocation of pennant numbers to boats. The Fairmile and Camper & Nicholson MGB pennant numbers came from the chronological allocation of Motor Launch (ML) pennants.

Apart from two flotillas of Fairmile Ds that were sent to the Mediterranean, all MGBs served around Britain, operating in the English Channel and North Sea, off the coasts of France, Belgium, the Netherlands, Denmark and Norway.

The reclassification of all MGBs to MTBs in 1943 brought an end to the MGB pennant numbers. All 71ft 6in British Power Boats were given MTB pennants starting with 412, and all boats still building were completed as MTBs (although many without torpedo tubes). All of the Fairmile Ds, except those in the Mediterranean, were reclassified as ‘all purpose’ MTBs, although like the 71ft 6in boats they retained their gun boat armament and were MGBs in all but name. 

Existing 70ft British Power Boat, Elco and Higgins MGBs were not reclassified and retained the MGB pennant, but many were struck from Admiralty lists and reallocated to the War Department or the Royal Air Force at around the same time. Only the few boats retained by the Admiralty, along with the Fairmile Cs, the Camper & Nicholson boats and the Mediterranean Fairmile Ds were still classified as MGBs at the end of the war.