Hethel Old Thorn is a 0.025-hectare (0.062-acre) nature reserve south-west of Norwich in Norfolk.

It is managed by the Norfolk Wildlife Trust.

[1] This is the smallest wildlife trust nature reserve in Britain, consisting of one ancient hawthorn tree, which may date to the thirteenth century.

In 1755 its girth was recorded as 9 feet 1 inch, and it has now decayed to a much smaller size, but it is still healthy.

[1]