Well I suppose they got hold of records from UK and elsewhere- the Ventures did a few tunes of the Shadows , Bert and others..

Didn't take but a week or two to get records ordered and sent by airmail back then!  I'm sure they kept an ear out for new material from outside of the USA- the Australian hit Bombora by our top instro group The Atlantics was also covered in the USA..

Bert is a great sentimental favourite of many Brits like me of a certain age group, he was on a kids TV show every week showing a new chord and playing his latest releases in the early '60's....he used big Golden Hofner electric archtops until about 1960/1, then he used Guild Starfires for a few years afterwards...usually with heavy strings, and British Selmer or Burns amps and a Selmer tape echo unit.  Much later he used Yamaha AE 200 model guitars and Marshall amps (he was an old friend of Jim Marshall)