Just checking it is brackets with a space inside followed by a plus sign.
Then it has to work on filename but does Grep and case sensitive search also need to be ticked, don't want to cause havoc in hundreds of thousands of files by making a mistake here.
Actually I have just found some filenames that have a space at the beginning and the suggested find and replace shown above did not work, does it only work in other positions in the name? Sorry for writing this in real time tried again and this time ticked all those other boxes for 'case sensitive', 'grep' and 'treat repeating fields as single string' and this time it did work - why?