Noisy Ancillary Drive Belt

[Vmax500]

My Chimaera 500 has recently taken to making a horrible squeaking/rattling noise from the ancillary drive belt upon a cold start. The noise stops after about 1-2 minutes of normal running. It sounds as if the belt is slipping or is too loose but as I say, it soon stops?!?££$

The belt 'feels' as taught as usual.

Does anyone have any ideas about how to adjust, clean, treat the belt or indeed eliminate the problem? At the moment my pride and joy sounds like a 1979 Vauxhall Chevette for the first 2 minutes every morning!!!

[Vmax500]

Thanks for the suggestions guys - that's my Sunday morning taken care of!