This is one of many tunnels that were used by the Northfleet cement works before it shut in 2008 it opened in the early 1900s I believe (cant find anything else older than that from the place) the tunnels were used to mine chalk and later on in WW2 most of them were converted into Air Raid shelters it was quite A hard explore as it was in A building site as they are building Houses on top of it and they have destroyed most of the tunnels but A few remain I will probaly end up going back next week Friday as its A bank holiday so their will be less people around