David,
As I understand it, MCIPD is not a qualification in itself, but rather a membership status of the CIPD.
Generally speaking, high calibre
HR people from the UK are well received in Australia, but it's never easy moving countries because you are usually up against candidates with local experience. Things like culture,
HR law and the
IR landscape all differ between Australia and the UK.
Furthermore, most senior opportunities are in Melbourne and Sydney, because that's where most of the head offices are, so your wife may struggle to secure a position in Perth at the same level as that which she has currently.
Probably not what you wanted to hear, but you may as well go into this with your eyes open!