John,
Thank you for your input once again; it is always very much appreciated.
The Fabric is glued to the wall so I spoke to Spencer Young at Prochem today who recommend that we brush first with a velvet boffin brush, hoover and then use a Prochem Dri-Chem Sponge, which is expanded latex foam for cleaning mainly, smoke damaged surfaces, fabrics and paper, but can clean general dust and mould, if used carefully.
I was not aware of these sponges before, so you learn something new all the time.
Regards,
Eric