After a bunch of phone calls, a visit to the DMV, and another bunch of phone calls here is what I got:
1) US-CBP (none importation/exportation expert): you need ITN and AES and you gotta export the car to Canada.
2) DMV: This title is Canadian, registered to a Canadian and has nothing to do with us. As far as we're concerned, this car is still Canadian. ...
This UK govt page describes the steps to be taken to import a vehicle into the UK. Here's the text from that page:
How to import a vehicle
You must complete certain steps as soon as you bring a vehicle into the UK permanently.
You can pay an importer or shipping company to do them for you.
Tell HM Revenue and Customs (HMRC) within 14 days that the ...