Professional to look at mould?

[MrsBeaver]

Am thinking about treating black mould in the corner of our bedroom ceiling (which faces an outside wall) with HG spray but just thought maybe I should get a professional in to look at the underlying cause

But what sort of tradesperson should I contact for this kind or problem?

for the most common cause, start by improving the ventilation to let the humidity out, and stop draping wet washing around the house or over radiators, if you do it.

For a less common cause, climb into the loft and look for signs of a leak in the roof or a pipe, including water running down sloping timbers to drip off nowhere near the leak.