From Gatwick Airport train to Farringdon Underground Station then Tube to Amersham Underground Station. 1 h 56 min £18. From South Terminal Bus Station bus to Heathrow Central Bus Station, bus to High Wycombe, Castle Street (Corporation Street), then bus to Old Amersham, Whielden Street (Whielden Green). 3 h 5 min £21. From London Gatwick Airport (LGW) drive to Amersham. 59 min £11. From London Gatwick Airport towncar to Amersham. 59 min £153.