There's more than one key? When did this happen? I assume that it'll be OK to jauntily hammer along with it in the proper key of Barton, no matter what sort of tuning it has. The golden rule is "if it's audible, join in" and as a matter of curiosity, establish what key it was in after the thunderous climax, when one has got one's breath back and the voices in the head have died down a bit.

Keys indeed! Harumph.