Hi, thanks guys thanks for the response
. Just to clarify a little - the person who told me about this tunnel said it was NEAR the T.A base he also mentioned Chetwyn(?, but I don't think he meant IN the base.
I do have doubts about the reliabilty of the person who told me this info, as the first time he told me this story he said he watched his friends go down the tunnel, while on second telling he says he went through it with them. So I hope nobody is on a wild goose chase with this one. Next time I see him i will try and get him to show me the entrances.