This is part of the London Transport system but 'private' operators providing the boats/crews. We sat on top deck enroute to Greenwich with a Cockney geezer driving and 'cracking wise'. NOT a tour guide he stresses, & his commentary was slightly sarcastic but amusing. Lots to see eastbound til Canary Wharves, then he's 'shtum' for a bit. Return trip was a smaller ship and an older gentler 'geezer' driving / commenting. Different spiel slightly, and even better. This journey is just under an hour each way and highly recommended.