I dunno, Tony, but I'm flattered you thought I would   My only thought on the topic is that the Savoy Opera Company had both the "main-theatre" company at the Savoy Theatre, and multiple touring companies playing regional cities and resort towns... so probably it was a movable feast, depending on venue size and available resources?  Two basses does seem a bit thumpy, I agree, especially with only two cellos.  Of course, it's always handy to have two string players on a desk, if only for the page-turns.

Sleep tight!!