Brighton Marathon finishes at Hove Lawns after a route that spends most of its distance in sight of the sea, so three nights in London afterward is as much a change of register as a change of city. April in London is unreliable in the specific way English spring usually is: warm enough for an outdoor lunch one afternoon, cold and wet enough for a museum the next, and rarely predictable more than a day out. The direct rail link from Brighton removes any need for a second short-haul flight or a complicated transfer: Southern and Thameslink services run to London Victoria and St Pancras respectively in around an hour, frequent enough through the day that timing a specific train matters less than showing up at the station.
Nights One to Three: London
London's identity needs no introduction, which is precisely the point for a runner three days post-marathon: the city offers enough indoor, low-walking-intensity options, museums, galleries, department stores, that a changeable April forecast is rarely a problem. The primary recovery asset worth naming specifically is the South Bank, a flat, paved riverside promenade running from Westminster Bridge past the London Eye, the National Theatre and Tate Modern to London Bridge, entirely step-free and around 4km end to end, walkable in sections rather than all at once. Regent's Canal towpath, from Little Venice to Camden or on to King's Cross, offers a similar flat, paved alternative away from the river crowds.
Secondary attractions worth naming: the British Museum (free entry, Bloomsbury), with enough ground-floor galleries to fill half a day without significant stairs; Borough Market, near London Bridge, for food that rewards slow browsing rather than a fixed itinerary; and Kew Gardens, in the city's southwest, for anyone wanting greenery and flat paths over indoor crowds, with entry around £20 and free-flowering spring displays typically well underway by April, though specific bloom timing varies year to year and is worth checking closer to the visit.
Where to stay: A hotel near Victoria station suits runners prioritising the direct rail link back to Brighton and onward to Gatwick; the area around King's Cross and St Pancras suits those connecting onward by Eurostar or wanting easy access to the British Library and Regent's Canal. Either area offers a wide range of hotel tiers from budget chains to full-service options.
Where to eat: Borough Market's stalls cover everything from a quick flatbread lunch to a sit-down oyster counter, and work well for a group with different appetites and no fixed plan. Dishoom, with several London branches, does an all-day breakfast naan roll that suits a recovery appetite better than most conventional London breakfasts.
Getting to the Airport
For Heathrow (LHR): the Piccadilly line runs directly from central London, around 50 minutes from most central stations, or the Heathrow Express from Paddington in 15 minutes at a higher fare. For Gatwick (LGW): the Gatwick Express from Victoria takes about 30 minutes, or a slower but cheaper Thameslink service from St Pancras and other central stations. Runners connecting through Gatwick can also route directly from Brighton without going into London first, worth considering if London is a stopover rather than the final destination before flying home.