This is not going to be of much use but there are some Australian dealers who are good. Problem is that I don't have a link on this computer. I'll check at work and see if I can help you. Problem may be however that it classes as part of a firearm and therefore subject to arms export restrictions. I got a new butt for my SMLE and a bayonet a few years ago and they arrived within a few days of placing an order.
This said have you tried the armourer at Bisley; he usually has a few Enfield bits. Contact is on the NSC/NRA web site.
Looks like you are sorted but herewith the link to Lawrence Ordnance in Australia. Doesn't look like they have any No 1 mags at the moment but they are a useful source of some Enfield parts and as I said are quick getting stuff to the UK.