Now the sun has finally come out...... I have been able to strip down my two external sofa's and can see that the mould has not only permeated the sofa cushion covers, the cushions, the external cover for the whole sofa it has also got into the "skin" of the sofa too!
I have heard various tricks from baking soda, alcohol, bleach (!!) so if anyone has the same problem or knows the best way to remove and also how to wash the cushion covers in the washing machine that would be a great help.
Incidentally, I cannot wash the cushions themselves in the machine as they have a feather interior.
All suggestions eagerly welcomed!!!