It will be something loose. Valve clearances don't rattle..

check all your nuts and bolts

its such a strange noise, it only happens when cold at around 3k 4k revs but it has been getting worse over the last two weeks

and surley if it was a bolt or a nut it wouldnt stop rattling at higher revs and wouldnt stop rattling when it was hotter

If it is a bolt or a nut it would be resonating and when the revs go higher then they don't rattle any more.

If it is a rattle and getting worse then are you sure it is ont internal to the motor?

Valve clearances don't rattle...

God knows what it is, its so strange how it only does it at low revs but its very distinctive and at any other time when it hots or higher in the rev range it seems to dissapear i cant get my head around it

Unles you have a properly broken it and you have engine damage then it is going to be something that is resonating at the certain revs.

Have you tried to listen to the innards - use a stethoscope, or a long screwdriver, pressed to the case and the handle to your ear..

I still stand by my previous statement about the chain - checked that for excessive play yet? Would take a few seconds to check.

Aye, good call. Does it rattle in neutral?

nope it aboustly fine even when its just sitting ticking over or you rev it when its in netural you cant hear anything its only when your moving and when its cold at about 3-5 k revs sounds like clattering bit like metal agaisnt metal

SO HAVE YOU TRIED CHECKING THE CHAIN YET?