LHR · One turn of the clock · published · checked
24 hours in London from LHR
London punishes the traveller who tries to see it. Twenty-four hours is the Tower, or the Eye and a boat, and a hotel on the Elizabeth line.
The private airport tour is for a gap of about six hours when you want the car to handle the return. It is not a budget add-on.
Out of the airport
Have the ETA, the visa, or the British or Irish passport settled before you are at the gate of the inbound flight. The border is not where you apply.
Elizabeth line from the terminal station. It serves Terminals 2 and 3, Terminal 4, and Terminal 5. Heathrow Express is the 15-minute train from Terminals 2 and 3 to Paddington, every 15 minutes, and it does not serve Terminal 4 without a change. Use Express when Paddington is the hotel. Use the Elizabeth line when the hotel is anywhere else on its route.
The plan
The Tower of London is two to three hours, including the Crown Jewels and a Yeoman Warder tour, if you already hold the ticket. No large suitcases. The Elizabeth line gets you as far as the centre. The last hop is a Tube or a walk, and that hop counts.
The London Eye is the short booking: about half an hour in the air, longer once you add the slot and the queue you hoped to skip. A fast-track time is the point of booking it on a layover. Pair it with a single Uber Boat hop if you want the river, not with the Tower on the same afternoon.
What to skip
The British Museum and the Tower and Westminster Abbey. A hop-on bus as a way of seeing everything. Any day trip.
A six-hour private loop from the terminal past Westminster, Buckingham Palace, St Paul's, and the Tower is a highlight reel from the car. Take it when the gap is long and the group price, from about $404, is a decision you have already made. Do not take it and also hold a museum ticket.
Back to Heathrow
Same railway, your actual terminal, three hours before a long-haul. Changing from the Elizabeth line onto a Terminal 4 train is not instantaneous.
A departure before about 08:00 belongs to a Heathrow hotel. The first trains are early. They are not a plan for a bleary 06:30 bag drop.