Portland spy ring 'could have been stopped four years earlier', files say

Declassified papers suggest wife of spy Harry Houghton told admiralty of his role in 1955

An infamous Soviet spy ring that passed on admiralty documents, including information on Britain’s first nuclear submarine, could have been stopped four years earlier, declassified documents suggest.

In 1961 the authorities exposed the Portland spy ring, named after the Dorset naval base from which the secrets were stolen, arresting and eventually convicting five Soviet agents.

Related: PM was not told Anthony Blunt was Soviet spy, archives reveal