Okay panic over,
Took all the modules out of the root, re downloaded and started again. This time I installed GridFieldBulkEditingTools & SortableGridField first and then installed your Gallery module and it seems to have cleared it's throat.
So only can guess that either one of the zips got corrupted during download or installing those two modules first then running yours made the difference.
Sorry to have troubled you & thanks for your time & for a great working gallery module, really appreciate you doing this.
Cheers once again,
Adam.