Well if it they got back to you with an automated message style email and it had your application number and the words, "This confirms that your application for permanent residence in Canada has been received by Citizenship and Immigration Canada (CIC) on xxxx," that's your AOR. Not sure if you mean someone just responded to you with the application number unofficially though.
I'm surprised about that request for a police check from the UK because CIC specifically states that one "must obtain a police certificate from each country or territory where you have lived for six consecutive months or longer since reaching the age of 18." I guess they are getting picky now by asking people who didn't quite make it to 6 months for one. God forbid you just take that 6 month rule literally and help someone get their visa a bit sooner :