The astonish mould & mildew blaster. from the pound shops. kills it good but it stinks strong for a while. this did better than the HG mould spray I bought. which was a lot more money. mould got into the skirting boards paint when I had a leak from above. the HG one didn't clear much of it. but the pound shop one killed it all the skirting was like new again like no mould was ever set into the paint. bleach is not a mould killer. you need a mould spray to kill it. but if you don't sort out. whatever is causing the mould. it will always be back no matter what you spray on it.
Bleach feeds the internal mold spores. Even though the surface may look bleached and clean, the remaining spores will root deeper, stronger and will often return worse than before. I Love HG mould remover, comes highly recommended.
Bleach is meant to make it multiply , Clean with mould and mildew and paint pva glue over the patch stops it coming back through , that’s what I was told by a professional who came out to treat mine and told me to do thus as it’s the cheapest option.