On Sunday, 13 January 2019 19:12:19 UTC, Tricky Dicky wrote:
I think I would look at your ventilation. Gable end walls are notorious for being cold especially if it faces into the prevailing weather direction. Since your kitchen is against this wall and is a major source of moisture as a result of cooking the likelihood your damp/black mould is a result of condensation. The cure is keep the room warmer and ventilate when cooking, if you do not have a ventilator than open a window. To remove existing black mould bleach does quite a good job.

Richard

Yes, definitely first thing to look at before looking for leaks etc.
You probably need a cooker extract hood (piping the damp air outside and with arrangements to let "replacement" air back in.)

Black mould is hard to get rid of when established. Lots of bleach!