What kind of hydrangea do you have? A photo or 2 would really help to asses the situation.

Thanks. I’ve tried to sending photos twice but with no luck. I don’t know what type of hydrangeas they are- the pink ones were from my dad’s garden so could be nearly twenty years old!£

Can't help with the brown patches but just wondering if your pruning method is the reason for poor flowering. If you cut back too hard you will cut off the buds that would contain flowering shoots.(re the sort they are, if they are round ball shaped flowers they will be mopheads.)

Thanks for that. The brown patches don’t look too bad on the photo as I had picked them off. I didn’t really prune it at all - just cut off the dead bits in the spring - but perhaps I did do as you suggested. Thanks again.