Despite some pioneering work in light craft in WWI, the Royal Navy's coastal forces lacked, due to the Admirality's scarce funds being poured into the capital ship programmes.
Never the less, the British Power Boat Company ( BPB ) pioneered a small 70 foot "hard chine" boat powered by huge aero engines, rated at over 1000 bhp each. This design became a standard, as a Motor Torpedo Boat, MTB, for attacks by torpedo on coastal shipping.
The foe of the "E" ( properly "S" ) boat was a great one - the German boats were larger, just as low, had heavier guns and deisel engines, although not as powerful for their weight, were far less likely to burn or explode. Unlike the high-octane aero engines of the MTB. Thus, the MGB, or Motor Gun Boat, evolved, armed with larger, and more, guns to deal with the threat.
Later, larger 100 and 117 foot combined MTB/MGB ( MGTB ) evolved, far more capable of handling the "E" boats than the earlier types, despite presenting a larger target.
Motor Launches ( ML ) for patrol, escort and local defence, Motor Anti-Submarine Boats ( MASB ) for light ASW escort of coastal convoys and Harbour Defence Motor Launches ( HDML ) for local defence and tender duties are included for completeness.