Yes, Ephemera is a great album, which I have on vinyl, with back cover photo of Pepper in London's Soho, where it was recorded. Saw him with the Jones/Lewis orchestra (Hanna/Mraz/Lewis rhythm section) in Manchester in 1978, so they must have visited Britain more than once in the seventies.
BillF. Ephemera was, I believe, recorded on tour with Thad and Mel in '73, so that was the year you would have seen the big band with that rhythm section. The pianist with the band in '78 was most likely Harold Danko and probably Bob Bowman on bass. It's easy for all the tours to kind of merge into one (especially 30+ years ago).
Thanks for jogging the memory! It was certainly no earlier than 1977 and Richard Davis may have been the bassist.