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The company which the Electoral Commission suspects may have been behind Britain's biggest political gift has no registered address – meaning it has failed to fulfil a key legal requirement – the BBC has found.

Rock Holdings is a firm registered in the Isle of Man and controlled by Leave.EU founder Arron Banks.

The Electoral Commission's ongoing investigation of Leave.EU funds was referred to the National Crime Agency.

Mr Banks denies any wrongdoing.

But BBC Newsnight has indicated that Rock Holdings has no official registered address on the Isle of Man and that it is therefore “in default”, meaning it is not is in accordance with company law on the island.

Meanwhile one of Mr Banks's companies has obstructed the BBC's attempt at ensure Rock Holdings' accounts – despite formally agreeing with Companies House that it would ensure the documents would be made publicly available.

Brexit campaign and Banks faculty ‘switched' Banks challenged over Leave.EU funds Leave.EU and Banks firm face PS1 35,000 fines Image caption Newsnight's John Sweeney went to Catbrain Lane to inspect the “publicly available” accounts, but was asked to leave.