Unknown small grebe

Observation - Unknown small grebe - UK and Ireland. Description: Small black and white grebe with long thin neck swimming and diving close to shore in quite rough conditions. didn't get a photo but another description could be a small merganser/grebe like bird, black and white in more of a pied wagtail pattern than the

Small black and white grebe with long thin neck swimming and diving close to shore in quite rough conditions. didn't get a photo but another description could be a small merganser/grebe like bird, black and white in more of a pied wagtail pattern than the black and white of grebes like the female black necked grebe which comes closest in my bird book. I'm guessing it was a black necked grebe?