Can anyone help with the correct right-hand fingering for a Diminished 7th on A-Grade 3 Trinity College?

I have a very old Trinity book of guitar scales and it states in the preface that 'right hand fingerings, where they occur in the arpeggios, are suggestions only, and need not be adhered to. Any logical, consistent formula will serve'. The dim 7ths don't actually show any fingering. Have you checked the latest syllabus on their website?