Priced up a job today, modern empty townhouse that had been rented out.
Inside the built-in cupboard in one bedroom that backed onto the shower of the ensuite next door was a damp dark patch in the corner that the owner said was due to the shower that had leaked next door, looked like mould and explained I weren't sure if much could be done to totally remove it, but they have asked me to do whatever I can.
Whats the best way to treat this?