Saving Cousin Billy

As you enter Ted Coney's Family Portraits you are met by over a 100 family photographs. I had noticed that a large one of Cousin Billy seemed to be turning from sepia (it must be a 100 years old) to bright yellow. A few days later, it had green mould on it and then there was a violent explosion of black mist! I took it off the wall and discovered black mould behind. This is on a wall which has a shower cubicle on the other side. Although it does not appear to be leaking there must be condensation or damp getting through. Luckily, Cousin Billy's face has not yet been affected (it is a full lenghth portrait) otherwise it would be a total distaster. Plumbers have been called and hopefully Johnathan will do what he can to save the rest of the photograph. Cousin Billy died young, so maybe there is an idea in there somewhere for a painting?