Members of the Royal Canadian Mounted Police were invited to replace the Queen's Life Guard of the Household Cavalry Regiment (HCR) at Buckingham Palace yesterday, 23 May. It is the first to date that this duty has been performed by a foreign unit. The only other British unit to mount The Queen's Life Guard is The King's Troop Royal Horse Artillery. More here.
Coincidentally, members of the HCR, considerably less resplendent than in the above picture, are currently here at Suffield participating in British Army training.