"Yes, but I know London's co-ordinates, and based on that I might be able to decipher where we are by comparing the sun's positions overhead now with the control--London is the control. I wouldn't be doing it if it didn't mean anything."
He wondered how much less people would speak if they actually thought about what it was they were going to say just a little bit more before they said it. Of course, so much of what Sherlock did--so much of what the science of deduction was--was picking up on the things people did without realising, so he supposed if people became more self-aware his work may be threatened.
But then again, Holmes didn't have enough faith in humanity to really be concerned.