There is an Ordnance Survey benchmark cut into the north west buttress of the tower.
It is about 4 feet (1.2M) above the ground and clearly visible.
It is also 45.053 metres above mean sea level, which is 147 feet 9¾ inches.
There are other benchmarks in Chiddingly: you can find them and information about them starting at
www.os.uk/osmaps.
Click “Places” at the top, followed by “benchmarks” on the left-hand side
menu.