'Copperhead' was a British deception planned as 'Telescope' (ii) and run in support of 'Overlord' in Normandy (25 May/June 1944).
In this undertaking an Australian actor, M. E. Clifton-James, was used to impersonate General Sir Bernard Montgomery, who had been designated as the commander-in-chief of the Allied 21st Army Group in 'Overlord', on a well-publicised visit to Gibraltar and North Africa. This was to suggest to the Germans that the invasion must be scheduled for some time in the future, since it would not be likely to take place in Montgomery’s absence.
On 25 May 1944 Clifton-James was flown from Northolt to Gibraltar in Prime Minister Winston Churchill’s personal transport aeroplane. At a reception at the governor-general’s house, hints were made about a supposed 'Plan 303' to invade southern France. German intelligence picked this up and ordered agents to find out what they could about Plan 303. Clifton-James was then flown to Algiers, where over the next few days he made a round of public appearances with General Sir Henry Maitland Wilson, the Allied commander-in-chief in the Mediterranean theatre. Clifton-James was then secretly flown to Cairo, where he stayed until the invasion in Normandy was well under way, and then returned to his original job after an absence of five weeks.