Thanks.
I lived in Liverpool at the time (1962-ish) and for many years after. As far as
I know, The Beatles shopped for guitar items mainly at Rushworth & Dreapers in
Whitechapel, a few doors from Brian Epstein's office over the former NEMS
store. The guitar department manager was the late Bob Hobbs, whose photo
(handing the J160Es to John and Paul) was displayed in the shop for years. Bob
was a great jazz player, very much in the style of Django, but on an electric
(a Gibson ES335TDC).
Bob was very much a guitar "guru" at the time (so was Jim Gretty at the rival
Hessy's shop), and would have recommended Gibson Sonomatic strings for any
electric. The original gauges were about 0.013" to 0.056". In those days, what
he and Jim recommended over the counter was pretty much what people used,
assuming they could afford it. Otherwise, players would use whatever cheaper
make was available - Black Diamond, Cathedral, etc. By late '62, when they got
their Gibson J160Es, I don't think expense was a problem for the Beatles. I
would go for Sonomatic in the absence of better evidence. And of course,
strings were not the hot subject they are today; back then, many players would
just ask for "...strings" without being bothered about the make.
Incidentally, the last time I was in Liverpool, I saw that the famous Bob
Hobbs/Beatles photograph had been replaced by one of the Beatles receiving
their guitars from the Managing Director, James Rushworth. It must have been
taken at the same time, but the substitution seems VERY petty to me. Bob
deserved better than that. He was a faithful employee of that shop (which still
exists).