https://www.youtube.com/watch?v=glELtCYFAyg
I found this clip on You Tube.
Britannia is seen entering Dartmouth in 1970, with all ensigns flying indicating that the Royal party are on board, probably to attend the Royal Regatta which was held every August. The film ends with her proceeding upriver so that she could be turned off Old Mill Creek and the RN College at Sandquay. She would then return and moor on the buoys opposite the town.
1970 was the year that my Dad took command of the Torquay pleasure cruiser Kiloran II, and I started to learn the ropes as deckhand, so we would have seen her every day that she was at the Regatta.
Regards.