Another dead mammal

Anyone good at dolphin identification? Or, more precisely, dead dolphins on their side off Goldcliff Pools identification? The photos below show a smallish cetacean which bobbed downstream with the tide at lunchtime, notable features included: a reasonably long, crescent shaped pectoral fin; all dark grey upperparts; an obvious pale area in front of the pectoral fin; a seemingly rounded tail fluke; and, though difficult to judge, a reasonably large size, probably 3-4m covered the length of the visible bits. Answers on a 'comment' please (click below). Also 14 Fieldfare, 30 Swallow and 1 Wheatear amongst the migrants, and 41 Avocet flushed by the farmer on his quad (again).