The four English airports mentioned in the crossword solutions are Gatwick, Heathrow, Luton, and Croydon. Gatwick is an international airport located in West Sussex, England, and is the second busiest airport in the United Kingdom. Heathrow is the busiest airport in the UK and is located in Hillingdon, London. Luton is a smaller airport located in Bedfordshire, England, and is mainly used for domestic flights. Croydon is an airport located in South London and is mainly used for private flights.