London in One Day: Westminster
In central London, Hyde Park and St James’s Park make a mostly traffic-free walk to Buckingham Palace, Big Ben and the Houses of Parliament, with the free National Gallery on Trafalgar Square close by.
Buckingham Palace’s gates and the Changing of the Guard
Buckingham Palace’s gilded front gates and forecourt are worth the walk on their own, and the Changing of the Guard adds the ceremony on the days it runs, usually alternate days and always worth confirming that morning. A guided Changing of the Guard tour takes care of the timing and the best place to stand.
Big Ben and the Houses of Parliament
Big Ben and the Houses of Parliament stand on the Thames at Westminster, where St James’s Park’s tree-lined paths end at Whitehall, and the view of both from Westminster Bridge costs nothing. Inside is a different matter: guided tours of the Houses of Parliament are the way in.
Hyde Park and the Serpentine
Hyde Park, the royal park just south of Paddington station, covers real distance across central London without touching a main road, and the Serpentine lake is a pleasant detour with a few minutes to spare.
Crossing town on the Underground is where luggage gets hard: fewer than half of London’s Tube stations have lifts or ramps.
Nelson’s Column and the National Gallery on Trafalgar Square
Trafalgar Square sits at the top of Whitehall, where Nelson’s Column and the fountains make a natural stopping point, and the National Gallery on its north side is free to enter, a solid fallback if the weather turns. Covent Garden’s street performers and covered market stalls are a short walk away for an extra hour without a fixed plan.
Paddington’s two trains to Heathrow
Take the Circle line from Westminster back to Paddington (about 20-25 minutes), then the Heathrow Express (roughly 15-20 minutes) or the slightly slower, cheaper Elizabeth line the rest of the way. Heathrow has four terminals, so build in at least two hours from central London to your gate rather than cutting it close, and collect the bag on the way so it never has to see a Tube staircase. Flying out of Gatwick instead changes the route; the Gatwick layover guide covers that one.
Frequently asked questions
What should I do during a layover in London?
Walk central London's royal parks: Hyde Park, then Buckingham Palace's gates, then St James's Park to Big Ben and the Houses of Parliament, all free to see from outside. With more time, Trafalgar Square and the free National Gallery are close by at the top of Whitehall. The Changing of the Guard runs on a limited schedule, so check it that morning, and skip it without losing the rest of the route if the timing doesn't work.
Do I need a UK ETA (Electronic Travel Authorisation) for a layover in London?
If your nationality needs one, yes. Leaving the airport to see London means passing UK border control, and travellers from ETA-eligible countries (the US, Canada, Australia and EU countries among them) need an approved Electronic Travel Authorisation to do that. Passengers who stay airside for a connection are currently exempt, but that exemption doesn't cover a trip into the city. Apply before you fly, since approval isn't instant.
Is this itinerary manageable if it's raining?
Mostly, though London rain makes the parks less appealing. The paths through Hyde Park and St James's Park are paved and fine underfoot, but if it's properly wet, swap the park walking for the National Gallery on Trafalgar Square or the covered arcades around Piccadilly instead.
How early should I head back to Heathrow for a late flight?
Leave central London at least two hours before your flight. Heathrow spans four terminals, and getting from the wrong one to check-in and through security can eat more time than the journey into the airport itself.
Is the walk from Paddington to Buckingham Palace and Big Ben stroller or wheelchair friendly?
The route itself is flat and mostly paved once you're through the parks, but plan your Tube (Underground) journey carefully: fewer than half of London's Underground stations have step-free access, so check before you rely on one to get back to Paddington.
Which train should I take from central London to Heathrow?
The Heathrow Express from Paddington is the fastest option at around 15-20 minutes to Heathrow Central, the station for Terminals 2 and 3, while the Elizabeth line covers the same route a little slower but for less money. The Elizabeth line calls at all four terminals, but the Heathrow Express stops only at Terminals 2 and 3 and Terminal 5, with a free transfer train on to Terminal 4, so check your boarding pass for which stop to get off at.