Edit: it turns out I was neither removed nor required to leave. No error was made.
I made an error on my last application for entry clearance while answering whether or not I have ever been removed from another country. I answered no–my 10 year visitor application was approved.
However, now, three years from the date of issue of the entry clearance I have realized that I was in fact “removed” from Canada about 8 months earlier. I used to be a Canadian Permanent resident but on entry, the IO found that I did not meet my residency requirements. I was allowed to enter but given a “departure order” to leave within 30 days. I did leave and have never needed to enter Canada again.
So now what? I still have seven years of entry clearance remaining. I did not mean to deceive anyone. I just had just assumed that a departure order was issued because my PR status had been revoked–and it wasn’t a “removal” per se–just a 30 day leave to enter. The removal order would not have been material to my UK application IMO. In fact, it would prove that ties to my home country are so strong I decided not to move to Canada legally. Do I do anything now? How do I proceed on my next entry clearance (which is very far away of course)?
I know Canada does not share immigration details about its citizens and PRs (which I was when I was “removed”). But I am no longer a permanent resident. Any suggestions for which lawyers I should contact?
You received an administrative removal from Canada (or what could be construed as an administrative removal) and you did not disclose it on an application for UK entry clearance. You are worried that you might have your visa revoked or be unable to successfully apply again.
First things first. You wrote…
The removal order would not have been material to my UK application
…and the Upper Tribunal wrote…
“When a direct question is asked, and answered untruthfully, there is
both a false representation and a non-disclosure; and it is not open
to an Appellant who gives an untruthful answer to a direct question in
an application form to say that the matter was not material.”
The head note to Kenya  UKUT 165 (IAC)
That’s a direct contradiction and since the high court has taken a position on it your argument on immateriality fails.
So now what?
You should get a reading on whether there has been deception or not. You cannot do this on the net because all you end up with are opinions from random people. Instead, it means arranging a consultation with a member of the UK Law Society (the organisation that accredits solicitors).
Ideally you need someone who has an acknowledged practice area in deception and there are several of them out there. Those guys attract a fee and I am guessing you would need to pay GBP 300 – 400, but that’s an onageristic guess.
If the solicitor decides there was no deception, he will give you a letter that explains his rationale. The letter will cite the relevant authorities like court decisions and so forth and you’re off the hook forever going forward.
If he decides that there was deception, he will give you a letter that explains his rationale and what you need to do about it. You can use that letter as a road map or simply ignore it and continue on the way you are doing now.
The act of getting a reading will crystallise your situation. If you are having stress about it, then it’s the way to relieve it.
See also duplicate posting: https://www.immigrationboards.com/general-uk-immigration-forum/removed-from-another-country-t226957.html