The National Crime Agency looked into allegations against Leave.EU and its founder Arron Banks.Read more
The company which the Electoral Commission suspects may have been behind Britain's biggest political donation 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, Bristol-based Arron Banks.
The Electoral Commission's ongoing investigation of Leave.EU funds was referred to the National Crime Agency.
Mr Banks denies any wrongdoing.