Is this some sort of grebe?

Is this some sort of grebe?

Observation - Is this some sort of grebe?. Description: Saw 3 of these birds in a marshy area in Aberthaw, south Wales. The water they were in come directly from the sea so is not freshwater. They were diving all the time and managed to get a quick snap while one was up. Sorry the photo is bad, they were far a

Saw 3 of these birds in a marshy area in Aberthaw, south Wales. The water they were in come directly from the sea so is not freshwater. They were diving all the time and managed to get a quick snap while one was up. Sorry the photo is bad, they were far away. These seemed to have a white rump and a dark black. I have had a trawl through the internet and I have come up with Black Necked Grebe, what do you think?