These four concerts were done in the middle of the A Day at the Races recordings (in fact, between the concerts in Edinburgh and Cardiff the band returned to London for some studio sessions) but they had a unique assortment of instruments, so it's worth placing them on a separate section. By this time John had already stripped off the paint from his 1968 bass as well, so they were both natural. From then on, and with only some exceptions, the 1968 bass would be his main.
At the end of the concert in Cardiff, Roger destroyed his kit (which was brand new), but he had a new one by the time they played Hyde Park - he'd signed a dealership with Ludwig so they sent him an endless supply of items from Chicago. As part of that dealership, Roger stopped using Meazzi toms and Shaftesbury stands.
This was the first tour including an acoustic set.
Gong [hit once at the end of Bohemian Rhapsody and Ogre Battle]
Triangle [Killer Queen]
Electric bass guitars
Electric six-string guitars
Acoustic guitar ['39]
Ukelele-banjo [Leroy Brown]
What about the recording sessions?
The fact John didn't have the Music Man before February 1977 rules out any chance that he may have used it for the Races album. Freddie possibly played the white Bechstein piano (same he used at Hyde Park) during the countryside sessions in Oxfordshire, and then two Bösendorfer's half-concert grands in London (You and I and Somebody to Love intro). Brian used a 1967 Baldwin Double-Six guitar on Long Away [not Burns as usually mentioned, although the companies had sort of merged then so it's not entirely wrong either]. That album also featured Roger playing electric rhythm guitar (most likely a Stratocaster) on Drowse. Brian played Vox electric piano on Teo Torriatte.