A large influence on the "British" sound was the BBC. Live music broadcasts were more widespread over there and the BBC made great efforts to have high quality sound. Many of their engineers made contributions to audio; Spencer Hughes[Spendor] and Dudley Harwood [Harbeth] both spent most of their careers at the BBC, developing Bextrane, the first widespread plastic material for cones. The speakers they developed were intended first and foremost for the reproduction of the human voice and they are still among the best at it. Not as "Analytical" as many American top end speakers but unfailingly musical.
The British Sound
Ok I know this sounds ridiculous but hear me out. The British sound is characterized as being laid back, mellow and unagressive in the treble. It struck me that England is a very humid environment. And in high humidity conditions, the treble is more pronounced and shrill. Musicians playing outside before a rainstorm call this condition the bloom before the thunderstorm. Ive read that this state can be explained by physics. The reason I thought of this again tonight is because right now the weather is extremely humid in central NC tonite. I listened to my stereo and I had to turn down the treble on my speaker controls. My AC has not run all day. I ask, is this why they tweak their designs. They are only trying to make musical equipment perspective of any environmental influences. Am I way out in left field? Then tell me why their products including speakers sound that way. Mike