The 66-year-old Prince Charles, the heir to the throne, will accompany the 88-year-old Queen to France to commemorate the 70th anniversary of the Allies' landings in Normandy in 1944, and attend some of the "key engagements" in place of his mother.
The move shows the two will "move towards what is in effect a job-share".
The press offices of the Queen and Prince Charles are to be merged, with the new office to be run by the Prince's staff, further signalling Prince Charles will assume more royal responsibility.
Queen, Prince Charles to move towards what is in effect a job-share
Last year, Prince Charles accompanied the Queen to attend the state opening of British parliament in May and represented his mother at the Commonwealth Heads of Government meeting in Colombo of Sri Lanka in November.
Thirty-two-year-old Prince William and 30-year-old Prince Harry, the two sons of Prince Charles and his first wife Diana, have both left their jobs as pilots in the military and taken on new careers recently in an alleged bid to prepare for more royal responsibilities.