Ha so I applied at around 8:30 pm Australian time.
Called up Amex UK and they said again I needed evidence of UK income, the second person was very pessimistic that only my AU tax return would suffice (she also asked her senior). Was told I'd get a reply in around 5 business days. I did actually tell them at the time I was waiting to start work in the UK. She said I could potentially wait until my first payslip.
Posted here at 9:20pm Australian time.
Woke up to an email sent at 1:30am Australian time saying I'd been approved!
It's a cracking deal - 95k Avios, 250 quid of travel credit and I'll also use 100 quid UK dining credit and 200 quid overseas dining credit (here in Australia) before I ditch it and get a pro rata refund.
Excellent! To be fair, the CS team (while better than Australia's, historically) are pretty uninformed about GT, they don't know how it works or what's acceptable (mostly). It's just not something they deal with often. A bit like transferring MR points between countries, sometimes you have to talk them through it before they believe it's possible, then eventually find a way to do it.
The financial review, GT, fraud and other such teams will be well aware of things like that, though you don't really want to voluntarily be talking to those teams haha (GT are fine of course). However, having been through FR, I've spoken to them and they aren't (I don't think) out to get you or trip you up, so they're pretty clear on what they need and, if your docs are unconventional (exactly such things as providing foreign payslips) they know what they can and can't accept - ANZ only producing bank statements every six months almost caused me an issue, as they were adament they needed one within the last 3x - luckily between the first and follow up call, ANZ had produced one, so problem solved!
Congrats though, that is a great deal. I've kept a UK Plat Charge for years now, the travel insurance alone is worth paying the annual fee, statement credits are just a bonus, but YMMV (and I haven't claimed since they switched from Axa to which ever company they use now...).