I just want to wrap my query up and point out that KLR142 was right - the engine mount beneath the torque rod was collapsed and the engine was clanging away on the metal. As others here have pointed out, if you have one bad mount you definitely need to check the others. After replacement the car isn...

Ok thanks for this. I've changed the plugs but will check the engine mount.

I hope you don't mind me coming in on an old thread but did you get this fixed?
I have a very similar sound with an xc70 T6. One garage has already replaced the top right mount but it had no effect on the noise.