Quick update - I think I found the problem !
I removed RH casing and then the stater clutch and the outer ring with the raised sections (for the pick up coils) is definitely loose and seems free to rotate independently to the main body.
I'm sure this is not right as timing would be all over the shop - so have ordered another one on ebay - fingers crossed !!
Thanks to all who offered help particularly johnnie5 who was spot on !

great to hear

shame you did so much work to find out its something simple

Mine broke down on me in tasmania , so it was a $100 tow back to the ferry and the ferry back to sydney and a trailer ride back home

and then about a year of scratching my head and getting the shits until i asked the board here ( the old one) and found the problem

as i had a couple of bikes i took the disk off the other bike , lined it up and my dad welded it in place

bike started straight away

people said why dont you take it to a mechanic ?? , i knew they would go through same things as me

but it was a bloody fantastic feeling to hear it start again knowing the hard work that went into it

Ok just to wrap this up - new starter clutch arrived, bolted it on and it fired up straightway no problem !

Don't know whether to laugh or cry but at least I'll know better next time

Either way thanks for all help guys

Good result.

In all likelihood this would have been the last thing to check anyway after all the fault finding and part swapping that you'd already done. Rare, but does happen!