Tunnels in Hampshire
The tunnels did exist – 2 different well known sources of mine have been down them – They contained a large quantity of Star Avia parts.
Zero timed Gipsy Queens came from their depths as did Vamprire bits and other goodies.
One of my contacts (a very reputable UK warbird man who owned a fleet of vintage jets) said that it was so long your torch would run out before you got to the end.
Sadly they were cleared by a scrap man probably mid to late 80’s.
Best place to check scapping records is the RAF Station records at Kew.
Its a well Known fact that the RAF burried and dumped lots of Kit on nearly every Airfield from world war one onwards.
Ive picked up a P type compass bowl that was dug up by Rabbits at a well known Scottish site.