I have water coming in around and down my chimney. Flashings are ok and have tried watersealing but still the same.

Do you have a rain guard cowl fitted and is all the pointing ok. If all the chimney stack has been taken down below the loft area it would make sense to remove the stack above roof line and tile over.

providing it is not a conservation area, remove the chimney completly and seal the roof would probably be the best long term option.

I agree with abowe removing is simple job and permanent solution otherwise is rain top on? pointing ok? and if it is flasching may be ok but felt isn't look in the loft is felt hanging down around chemney? it should be sticking to chemney and folded up. Some times battens don't hold felt and when it collapse in side you have leak Gegory Zwolski P.S I am servicing mostly roofs for estate agents over 400 in my town alone so I see the same problems all the time