Didn't Freddie get a different piano around that time?
Yeah. Before November 1977, he'd just use whatever was available, including a Wurly on at least one occasion.
For the famous Xmas Eve concert in '75, he rented the same white Bechstein he'd recorded the album with (and the same he'd used for the 'Bo Rhap' video).
At the Exhibition Centre he played a Steinway... but not the same Steinway he got later on...