Hi Eamonn - I have a pdf of the section with the theorbo guitar pieces which I will try to attach.  Is your instrument guitar-shaped?   Monica

Granata1659p.74-143.pdf

I wondered how big it was and in particular what the string lengths on the fingerboard and the open basses were.  At least one person is of the opinion that the open diapasons on Granata's instrument were tuned in the upper octave i.e. the strings on the fingerboard were fully re-entrant and the first diapason was tuned to the same pitch of the 3rd course descending thereafter.  He maintains that as shown in the illustration the bass extension is not long enough for a true bass register.  Incidentally have you managed to put your dissertation on line as I would quite like to read it.   Monica