Hre are a few pages from the Wiltshire times

http://tinyurl.com/6f9sthm

http://tinyurl.com/6bbxhb6

http://tinyurl.com/69ke4y8



http://tinyurl.com/5watn7k

Nigel Spreadbury-Clews, the man who oversees the underground operations as well as those above, said: "When you are down there you are literally just feet away from the Box Tunnel and you can hear the trains rattle through.We now use the tunnels mainly for sewage, waste disposal and storage. We do other things too but it is definitely not being used to keep aliens, as some might believe."

Thats what the smell is at the end of Box tunnel sewage.