Pasted from knockholt list:

Tent
Sleeping bag
Airbed
Seat - you can get a folding garden chair in woolies or argos for about £5!
Firewood - If you have a van or large vehicle extra wood is always welcome!
Musical instrument
Spare strings
Food - There are no shops nearby.
A torch
Calor gaz cooker
Pot & pan
Tin opener
Water container/bottle
Soap/toothbrush/towel
Warm clothes
Umbrella
Sun block
Cigarettes
Matches/lighter
Booze
Cash
Condoms!
Beer money