CAMERAS were rolling at Minsmere as engineers and archaeologists from the BBC's Meet the Ancestors team, helped by volunteers from Otley College, tried to unlock a mystery surrounding an ancient British causeway.

CAMERAS were rolling at Minsmere as engineers and archaeologists from the BBC's Meet the Ancestors team, helped by volunteers from Otley College, tried to unlock a mystery surrounding an ancient British causeway.

Scholars are fascinated by how iron age people managed to build the timber causeway, discovered recently in Lincolnshire.

What interests them are a series of about 160 supporting posts, which were driven into the ancient marshland to a depth of around 3.5m.

A BBC2 programme, Celtic Causeway, due to be screened next month, examines the find. It charts the efforts of some of Britain's leading prehistoric archaeologists at Minsmere RSPB reserve to carry out experiments to find out how they might have done it.

The spot was chosen because the terrain is similar to what it would have been at the Lincolnshire site when the causeway was built.

Over the weekend, the team tried out three different methods for driving the posts into the ground.

Hailstorms, high winds, heavy snow and sunshine failed to dampen spirits among the crew and around 28 volunteers from Otley College.

"We actually had four seasons in one day," said producer Suzanne Levy as she described their efforts.

The Meet the Ancestors programme will be broadcast on BBC2, on Wednesday, March 27 at 9pm.