The line that runs straight through
Thameslink is the railway that crosses London instead of stopping at its edge. Its trains come in from the north through Farringdon, City Thameslink and Blackfriars, cross the river, call at London Bridge, then head south through East Croydon to Gatwick Airport and Brighton. For anyone staying in the City or on the south bank, that makes Gatwick the most convenient of the big airports: no change of train and no trip west to Victoria for the express.
From London Bridge the ride takes around half an hour. Contactless cards and Oyster are accepted all the way to the airport, so there is no ticket queue unless you want one. Trains run frequently through the day and into the evening; very early and very late the pattern is thinner, and weekend engineering work sometimes interrupts it, so check the times for your date rather than assuming.
Guests staying north of the water have the same direct run. City Thameslink sits between Ludgate Hill and Holborn Viaduct, and Blackfriars stretches its platforms right across the Thames, the only station in London to do so; on a clear morning its windows take in St Paul's and the Shard in a single sweep.
Thirty minutes is the train, not the journey
The half hour is platform to platform. Around it sit the walk from your hotel, the wait for the next departure, and at the far end the short walk from Gatwick's station into the South Terminal, which it adjoins. For North Terminal there is a free automatic shuttle between the two, a ride of a couple of minutes plus the wait for it. Then bag drop, security and the long corridors to the gate.
So work backwards from the time your airline wants you at the gate, add the half hour on the train, and then add a generous margin for everything around it. The airline and the airport publish their own recommendations for check-in and security, and those, not this entry, are the numbers to trust. A summer Saturday deserves more margin than a Tuesday in November.
Where to sleep: by the station or by the runway
There are two sound answers. The first is a room near London Bridge: SE1 9SG across the road from the station, the hotel floors at SE1 9QU above the platforms, SE1 2BY a few minutes east on More London. You spend the evening in the city, wake up in it, and the airport is one train away. It suits a mid-morning departure, when the trains are back at their daytime rhythm.
The second is to go down the night before and sleep at the airport itself. The hotel at RH6 0PH connects to the North Terminal by a covered bridge, and RH6 0LL joins the South Terminal the same way, so the morning becomes a short stroll with a suitcase. This suits the very early flights, when even the first train of the day feels too close for comfort. The trade is an evening spent somewhere with rather less to offer than SE1.
Shaping the evening around the alarm
If you stay in town, the evening has a firm end and a relaxed middle. Pack before dinner, so that nothing is left for midnight. Choose a table within ten minutes of the hotel, which around London Bridge is easy. Two hours at £500 from seven covers dinner and a walk along the river and returns you to your room by nine. The four-hour dinner date, £900, suits a later flight.
Put the passport, the boarding pass and the phone charger in one place before you go out. It sounds like a small thing. It is the difference between an evening that ends calmly and one that ends with a search under the bed at six in the morning.
If a companion stays with you through the night, the ten-hour overnight at £1,800 can be timed to end as you leave for the train. Give the desk the flight time and the departure you intend to catch, and the booking is built backwards from both. She leaves when you do, and the morning stays yours.
At the airport the booking changes shape. At a Heathrow or Gatwick hotel the shortest booking is three hours, £700, her travel time falls within those hours, and the fare back appears in one figure before you confirm. The travel companion page covers airport hotels and journeys further afield, and the rates page shows each length.
The reverse run: landing at Gatwick
The same line works in the other direction. Land in the evening, clear the airport, take Thameslink north, and within the hour you are crossing the concourse at London Bridge with the Shard overhead. Message the desk from the train with your hotel and an estimated arrival; she comes to the hotel after you have checked in and put the bags down, an hour or more from the desk's confirmation, and never to a platform.
Flights run late. If yours does, tell the desk the moment you know rather than when you land, and the start is moved to match, as far as the notice allows. The London Bridge Station page lists the hotels a few minutes from the barriers, for the nights when a short walk is all anyone wants.
Who travels light
Laura has ridden a good share of the railways of Italy and treats a timetable as a challenge rather than a constraint; she is good company on the evening before any departure. Nora works best with a day's warning and does not mind a late landing. Samanta, who can judge a hotel from its lobby in under a minute, confirms her dinners by three and arrives exactly on time, which is the quality you want when there is a flight to catch. Cindy keeps to daylight, lunchtime to sunset, and suits an afternoon or evening departure better than a dawn one.
Laura and Nora are both on the toned page, while Nora and Cindy also appear among the blondes.