Thanks Andrew,
I checked this data against my ssystem.ini and I amended every value to provide extra precision.
The ssystem.ini file is in %ProgramFiles%\Stellarium\data, as you said earlier, then ran Stellarium - no change.
I then changed the ssystem.ini in the Users%APPDATA%\Stellarium\data folder (I am the admin and only user anyway of this pc) and then ran Stellarium - and 1p/Halley is not found on the database at all
I am uninstalling and reinstalling the software and will try again.