However, one devotee appears not to have been told.
Adding to her embarrassment, the tall sunbather was then beckoned over, still topless, and tasked with taking photos of the star with her friends, while his new wife Nancy Shevell looked on.
The young woman wore tiny string bikini bottoms but attempted to keep some of her modesty intact by covering herself with her arms.
One of her friends posed for a photograph with the former Beatle, who was wearing colourful pair of swimming shorts, a brown T-shirt and matching baseball cap. They used a camera-phone to take the photograph.
The star posed up just days after he publicly bemoaned the attention he receives from members of the public, especially those who use their mobile phones to take pictures of him.
'And increasingly people just don't seem to understand that. That sometimes causes unpleasant scenes.