Black mold....

[Admiral]

Thanks for that Fred and La Brasserie.

I'm going for the vinegar and bicarb option because I like the sound of it.

I will purchase a couple of masques d'hygiene and a tub of bicarb ahead of Madame Admiral cleaning the stuff off the wall.

The only possible problem here is that I haven't told her she's doing the job. After all, gentlemen don't get their hands dirty.