Originally Posted by
ffsim
That was the first thing that came to mind when reading the OP. However, there's no verbiage on AC's MLL page that suggests you can't buy access for an international MLL...
To the best of my recollection, I was not offered to buy access for YYZ-LHR (just prior to making early recognition to 50K last year) and had forgotten that I did not still have it (as I was 50K the last time I flew internationally with time for lounging.) Had to go to PP lounge instead.
The AC website is outdated -
the MLL information page still says E35K can choose international lounge access as a select privilege, but the Altitude page says nothing of the kind. It does say that Flex can buy MLL access (without saying anything about dom/TB only), and although you cannot walk up and pay your way in, it says that as long as one passenger has prepurchased access, they can pay at the door for additional guests.
So, very interesting. Hope OP comes back to report.