Hi all,
I filled up the form 1405 and sent it to Australia House along with mine and my wife's passport. I also attached the visa grant letter and a covering letter. I called Australia House to confirm if i could put my UK debit card details on the form and they said yes. Sent it out on a monday through trackable Royal mail along with a prepaid self addressed envelope(trackable), cost me £12 (approx in total) and received them back on saturday the same week. £163 got debited from my account for both passport labels.
Address :
Australia House,
Visa Evidencing Unit,
Migration Branch,
Strand, London
WC2B 4LA
Hope it helps.