The marker is approximate. However for the accuracy of the then Royal Navy Engineers/Survayers I am pretty sure the stone used to sit exactly on the 114'30" E longitude.
Thanks for JW for this piece of Old News. Back in 2007 archeologists in Shenzhen had discover this stone marker at the tip of the Xichong (西沖)。 It was the boundary marker setup by the British for the seaward boundary concerning the taking (or lease, depends on how you look at it) of the New Territories. <Read more ...>
Location is just a speculation. It is based upon a present day village called Ying Pun Ha (營盤下)。Ying Pun (營盤) means a military camp and Ha (下) means under/below. The name of the village literally means "the village below the military camp' in English. If the beacon was there it would be somewhere along the ridge.