HMY Britannia was commissioned and crewed by the Royal Navy, and like other RN vessels would carry Royal Marines as part of the “Ships Force Protection Team”. With the Head of State onboard, and visiting foreign ports ... it would have made sense to have a lot of amphibious infantry on hand, just in case.
I knew someone who was having a quiet walk with their dog on a secluded beach in the Outer Hebrides when they were surprised to find marines landing and running past them into the dunes and not speaking to them.
A few minutes later Elizabeth and Margaret arrived with their dogs - an obligatory conversation about the weather and respective dog breeds was had before all the visitors piled back into their boats.
