The agreement only existed for live performances. A long time before that the Beatles used other stuff. I have a book on The Beatles equipment. There's a pic of Mal the roadie, sent down to the biggest London retailer who carried Fender and Ric and Martin, he bought back two Sonic Blue '64 Strats in 1965 as soon as the embargo on imports from the US ended. The studio from the early 60s was filled with blonde then brown then BF and SF Fenders. Some of it personally imported. Apparently you can hear John's on 'Help'. John apparently fondly remembered his Tweed Deluxe, there's a pic in 68 or 69 with a Deluxe (non-reverb) being unboxed. There's also a picture of Paul, wearing an upside down right handed sunburst rosewood board Tele leaning over a Selmer Treble'n'Bass 50 in the studio. As well as cheap guitars like George's classical Ramirez used on Norwegian Wood, they had Martins, Epiphone Casinos (John, George and Paul all had one) and used Epiphone AJ acoustics fitted with the electric-type pickup under the edge of the fingerboard. One of George and John's favourite studio toys was a Fender VI, the baritone sixstring longneck. The Beatles did use Vox in the studio, you can hear the SS stuff in things like Dr Robert, Taxman.