Shooting on "Edge of Darkness" began on 9 July 1984 and ran for five months until 5 December 1984. Location filming took place in London (including the Barbican Arts Centre, BBC Television Centre and the Hilton International Kensington), Yorkshire (including the headquarters of the West Yorkshire Police in Bradford, the Middleton Railway, the headquarters of Systime Computers (now the Arlington Business Centre) in Leeds where Craven hacks into the MI5 computer and at Westwood Cottage, Ilkley (for Craven's home), Scotland (including the Gleneagles Hotel, where Jedburgh addresses the NATO conference and also where President Reagan's Reykjavík policy was formulated) and Wales (including Clogau Gold Mine and Manod, Blaenau Ffestiniog doubling as Northmoor with the hot cell a set constructed at a factory in Penygroes). Throughout the entire shoot, the production continued to be known as "Magnox"; the title "Dark Forces" was briefly considered before the serial was renamed "Edge of Darkness" in April 1985. As the shoot progressed it became apparent to the cast and crew that they had a potential hit on their hands; Bob Peck recalled, "I think we knew when we were making it that it was a good piece of work" while Kennedy Martin told reporters "I haven't had this feeling about something for 20 years. It's wonderful, after all this time, to get something that actually works".