Troy Steadman wrote:

It isn't a tunnel, it's a roundabout on top of the A3 in a cutting,
nowadays a very ordinary intersection but in it's time quite something.
As was the "Ace of Spades" roadhouse on the old roundabout which had not
only a swimming pool but also an airfield.

An airfield!? Where was that then?

The Ace of Spades had a major fire many many years ago and AFAIK the
only thing that's left is the facade, still with a metal ace symbol
sticking out of the front. The back of the building is a semi-modern
warehouse type building connected to the shop unit next door. It was a
dinner-dance place for a long while but is now a large golf warehouse.

Incidently, my school was next door to the Ace of Spades roundabout.