If staying near Hammersmith or Earl’s Court, the Piccadilly line offers a straightforward

https://augustdxbx383.huicopper.com/getting-to-heathrow-from-gatwick-easiest-inter-airport-transfers

If staying near Hammersmith or Earl’s Court, the Piccadilly line offers a straightforward, single-seat ride to Heathrow without needing to change trains.