This is probably a difficult question to answer because I’ve been giving it quite a bit of thought for at least – oh,….. 5 minutes! :^0
For me it could be one of three things:
#1 Freshly ground, just-brewed coffee
#2 Garlic is more or less an essential
#3 Fox’s Glacier Mints
([i]without which TR would have no knowledge of OldER Mycroft[/i])