Thanks Neo appreciate the advice…. Chain has been well maintained and have already checked…. The noise sounds like every link is striking/fouling something rather than a single link that would change as speed changes…. Sounds same as if you dragged a fingernail over a comb.
I think I will take rear wheel off this weekend and make sure everything is correct…. I feel it’s an alignment issue of some sort…..
On the plus side it is a long weekend