Guillemots have the smallest breeding territory of any British bird. They nest in dense groups packed onto bare cliff ledges. Their single elongated egg is highly variable in both colour and markings which the parents learn to recognise so they don't end up bringing up the wrong chick in such crowded conditions. They are easy to photograph on their nesting ledges but fiendishly difficult to photograph in flight. Their flight is rapid and their small wings are just a blur. I photographed this individual at Bempton Cliffs in East Yorkshire.
In America this species is known as the Common Murre (rhymes with blur), and to confuse things further they also have (Pigeon & Black) Guillemots. I have been corrected many times in Canada when I have called this species a Guillemot. Two nations divided by a common language.