New Swim-Buddy

Having been away from home so much this summer, this is only my second sea-swim. Was missing my usual swim-buddy (my daughter), till along came a feathery friend to enjoy the water with me. As s/he was still there after I'd come out to fetch my camera, here's my blip - with an additional component taken by Mr PP.

Please can anyone identify the bird? Thought it might be in the grebe family, but failed to find it in my bird books so far. It was very relaxed in the warm, late afternoon sunshine. As were Mr PP and I!

Thanks for all the nice comments on my yesterblipped collage.