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Just reading about that. I hope they can open it up to the public. (Wouldn't fancy crawling down a rabbit hole)
There have been plenty of Urbex trips to it in the past. It was also articled in 2012 in the Daily Mail, of which it gave the location, so I found out today.
There is an Urbex site with it on, but if Swim says the owner doesn't want to be known then I won't put it up, but I think it's fairly common knowledge by the Urban Explorers.
The owner seems to have allowed it to be used for various purposes over the years .
There are also discrepancies as to whether it is as old as stated or could have been made in the first half of the 19th century. Looking at Royston cave as a comparison, there is nothing which shows the symbols of a Knights Templar's cave.
Royston Cave in Hertfordshire looks more like a Knights Templar's Cave.