DAVID Cameron is facing calls from a leading land reform campaigner to state his true position on Highland estates being owned by offshore companies after his summer break in Jura.

Andy Wightman has raised questions about the apparently complex ownership of the Bahamas-­registered 18,736-acre Tarbert Estate.

The Prime Minister, his wife Samantha and their three children stayed on the inner Hebridean island last week before moving on to Polzeath, Cornwall.

The family have enjoyed holidays there before where Samatha's stepfather Viscount Astor's family have landed interests. But Tarbert is owned by Ginge Manor Estates Limited based in Nassau and there is no means of verifying whether the viscount's children are the beneficial owners.

Mr Wightman, who wrote Who Owns Scotland and The Poor Had No Lawyers, said: "Tarbert Estate is popularly believed to be owned by Mr Cameron's stepfather-in-law, William Astor. In fact, it is owned by Ginge Manor Estates Ltd, registered at PMB 58, Nassau, Bahamas."

Ginge Manor is also an Oxfordshire manor house where Mr Cameron married.

Lord Astor denied claims by Mr Wightman he had not declared it in the Lords Register of Interests. He said he pays full UK tax.

He added the Bahamas company was North Jura Ltd, but he changed it to Ginge Manor Estate when he bought it as a teenager. Lord Astor said he bought Ginge Manor, but didn't change the name, adding: "Perhaps I should have, but 40 years ago I did not expect to have a stepson-in-law as PM."

A Downing Street ­spokesman said ownership was registered in the Bahamas for historical reasons.