Freelander 2 XS TD4 Rattle on acceleration

Hi Guys, a mystery noise coming from somewhere under my Freelander. Its a knocking rattle that sounds like a tin sheet hitting something rotating. Not always there, but cornering can start it off, then it is there during acceleration, particularly up hill, and sometimes stops when cruising. I've crawled under and tugged on anything that might move; nothing found. There is a recording of it here: https://youtu.be/pTzpgHYvGEg Any suggestions very welcome - I haven't got much hair left.