For grade 8 aurals, I don't find the syllabus totally clear as to all the possibilities. What I think it means is:

First a major key will be played. The modulation will be one of:

Dominant major (I know you only have say dominant, but putting major makes it clearer)
Subdominant major
Relative minor
Dominant minor
(Confirmation that test will not be subdominant minor please?)

Then another from a minor key:
Relative major
Dominant minor
Subdominant minor (not totally sure if that could be asked)
Dominant major

Please could someone check and correct if necessary? Thanks!

Ooh. One more quick question: Would an inversion of chord 5 ever be used to form a perfect cadence?

Almost correct...

The possibilities for the modulation part of the Grade 8 Aural tests are....

Dominant (Major - and, possibly, Minor in the case of starting in a Minor tonic key )
Subdominant (Major / Minor, depending on original Tonic key )
Relative Key

(Previously, the Supertonic Minor was also expected but I believe this has now been removed as a possibility.)

Great, thanks, so if I've understood that right, I was right to begin with apart from there being no minor-dominant major possibility.

EDIT: Actually, I'm still not totally sure if I understand.

Here is my revised list:

Major key:

Relative minor
Dominant major
Subdominant major

(so basically major is as grade 7)

Minor key:

Relative major
Dominant major/minor (just have to specify dominant)
Subdominant minor

Thank you!!