As a follow up to this, I have just renewed my UK passport by post from Sydney and the key dates were;
9 January - applied online
10 January - posted old passport to UK using regular post
26 January - passport office acknowledges receipt
30 January - passport approved
31 January - passport printed and posted
5 February - passport received via DHL courier
So the biggest delay seems to be the postal service. Once the passport was received processing was pretty quick.
