Tambourine when cold

Just looked at the Rimmer's catalogue diagrams and the non-air setup doesn't have the pulley. 
Apologies if I caused you concern.

No need.for apology. Only in my second year of ownership. Still at the dating stage.

And to close this one, the belt was changed and thenoise has stopped.
I have heard many a belt squeal but never intermittent castanets.

Polyrib belts make a whole different set of noises than the old fashioned vee belts, the noises can be caused by pitting or corrosion of the pulley surface, surface glazing of either the belt or pulley, contamination, misalignment and tracking of pulleys, incorrect tension adjustment, small cracks in the friction surface of the belts and hardening of he belt material due to age or thermal stress.
Sometimes there are minor noises that are amplified by weird harmonic effects.

Indeed Cob. I would not have put money on it though.

I agree