[blogging from a pub….]

If you should happen to be going between the National Archives/Kew Gardens and the British Library/Russell Square/King’s Cross area, change when you are above ground, at Hammersmith or Baron’s Court. Then it’s just a matter of stepping across the platform.

If you should happen to be toting luggage on that route, for a half-day at the archives before going to the airport (not uncommon): for the District Line—Kew Gardens uses the outside door, but all the stations between Kew and Baron’s Court use the center door, so you can safely block the outside door with your baggage. Picadilly trains normally have good places to put luggage.