went out in my neighbours boat on the weekend - around the Mew Stone by plymouth - it was a beautiful day, and then about 50yrds away we saw what looked like a basking shark - but as it got closer we noticed it only had the one fin - i.e. no shark tail fin. we could see what at first we thought to be the 'sharks' large white mouth open, but as we edged closer it looked liked the side of the fish. we got to within about 15yrs b4 it spotted us and darted off but im sure it must have been a sunfish - large roundish sides, quite short for the size of fish and a bloody great dorsal fin for the length of fish. Has anyone else seen them around?