So from what I have read so far, a semiautomatic rifle gave a solider quite a lot of firepower compared to a bolt action rifle.
Why exactly is it, that Britain (seemingly?) never adopted one during WW2 (Even after meeting German semiautos (The G41/43))?
I'd imagine that getting one wasn't the problem (The US already supplied Tanks, it couldn't have been that difficult to throw in some M1's, right?)
Was it something with the British infantry tactics that made the usage of semiautos superfluous?
The US did supply M1 Garands, around late 1940, early 1941. These were early models with the gas traps. Most were painted with a red band to signify they were not chambered in .303.
Most were put in storage but some were issued to airfield guards and some sources state a few were "liberated" from storage by commandos.
All in all its estimated around 3,000 or so we're sent to England. Though a ship carrying 50,000 was sunk. All were sold in the US surplus market in the 1950s and 1960s.
Follow up question: Does anyone know what rate of fire the British troops could deliver with the Lee Enfield, V.S. what American troops to could accomplish under similar conditions with the Garand?
[Edit] Specifically, what rates of fire they were trained to deliver
To add to /u/SerendipitouslySane 's excellent answer, a major factor for the British army was the consumption of ammunition - something that is a issue to this day.
With an automatic weapon, the soldier can empty a full magazine within a few seconds whilst suffering from high recoil and loss of accuracy. This means that not only do the supply lines have to produce and deliver more ammunition but the soldier has to carry more of it.