Excavation work on the longest road tunnel under land in the UK has begun.

The tunnel will improve a notorious traffic bottleneck on the A3 - the only trunk road connecting Portsmouth with London.

The £371 million scheme involves dualling the last remaining section of the A3, as well as creating a two-bore tunnel to carry the 30,000 vehicles a day that currently pass through the Surrey Hills Area of Outstanding Natural Beauty.

The tunnel will remove all traces of the existing road from the landscape, which includes the famous Devil's Punch Bowl, a site of Special Scientific Interest.