Another reason US instruments were few and far between in the UK back then. . . was price. I bought my Fender Precision in 1969 for just over £90. I was living in Brussels and they gave me a discount price because I was a pro musician. The UK didn't give discounts on musical instruments. Others were allowed reduced tax on "tools of the trade" like cameras but musicians had to pay full whack. So my £90 was actually about £122 in the UK and that would have been about £1900 in today's money. Very few working musicians in the UK could afford that, which why so many were using Framus, Hofner, Burns, Kay etc.