This month we discovered black mold (the dangerous kind) in a situation just like yours: leaking water from a plumbing valve between two sealed walls. When my husband and then ServPro (a mold remediation company) started taking the wall apart and dragging out the offensive building materials, my usually passive candida count went through the roof and now I'm dealing with trying to get all the mold spores out of the house. They fly around EVERYWHERE!! We've tried to keep the room where the damage is closed off, but it's our bedroom and the master bath and walk-in closet. Oh Boy! What a problem! Anyway... you may have spores still in your house, especially if you live in the UK. That's a mold-loving damp climate. There are sporicide products that you can spray on surfaces, but you would probably need to stay out of the house for at least a couple days and let it air out. That's what I'll have to do once the reconstruction crew is all finished.