OK Guys, the results are in:
I have checked the front sprocket is tight, (it is, tab washer is secure also)
All the bodywork panels are tight and don't rattle.
I can't get any movement on the chain when I attempt to pull it rearwards from the rear sprocket so I dont think the chain is is showing any sign of wear (3600 miles from new) and it is well lubricated.
All the aforementioned bolts are tight.
I have further loosened the chain so it does now (just) touch the underside of the swing arm if pushed upwards hard.
Tomorrows ride will tell if there is any difference with the noise.......