Freelander subframe noise

[Aida]

Hope someone can help.........
I've a 1999 petrol Freelander.
Had an annoying clicking sound on occasional cornering which has become slightly louder over last 2 years or so.
Got the wife to drive round the block to identify it better with me crouched in the back.
It's coming from the nut/metal plate assembly within the "guttering" onto which the subframe is mounted.
Very difficult to access, only a 1" inspection hole to view through.
Loosened bolt and found plate has some movement, as bolt is "twiddled" side to side. Nut/plate cannot be removed however as held in place by folded "legs" which are bent to grip onto "guttering". My feeling is that as the bolt is tightened, the plate turns slightly so plate doesn't sit snugly in "guttering" and flip-flops under certain conditions.
Local LR garage said it was the link arm bushes. Replaced them with shiny new ones and guess what.......... no change.
Can't put a weld in due to 1" access hole and can only guess that some sort of cut out & weld is only solution, which would be a shame as bodywork is spotless, even underside.
Compared give in plate by loosening rear mounting bolt - less twiddle noted, but now I'm sure that's joined in the clicking.
Tried all combinations of overtightening etc. but no change, other than perhaps a day or so before noise returns.
Handling perfect in all conditions, noise only on hard cornering but very unnerving.
Any suggestions?