No — show the mobile ticket on your phone to the crew or ticket office at the pier before boarding.

Greenwich is the longer run (about an hour each way) and drops you near the market, the Cutty Sark and the Royal Observatory. Tower Bridge is a shorter 30-minute hop past the Tower of London and St Katharine Docks.

Return times follow the operator's timetable and shift slightly with the tide — check thamesriversightseeing.com or ask the crew when you board, and confirm the last sailing before you wander off in Greenwich.

Under-5s travel free without a ticket. Anyone older needs their own ticket at the appropriate price.

No, there's covered seating too, but the open deck is where the photos happen. It's breezy even on a calm day, so bring a layer.

Yes, on a round-trip ticket — disembark, explore at your pace, then board any later sailing back to Westminster on the same timetable.

That's fine — the ticket doesn't force you to use every leg, you just won't get a refund for the unused half.