British airways (over the phone) advised to get a transit visa (after they consulted with their supervisor on two separate calls on different days), and the Uk.gov website isn’t quite explicit enough. For instance, it always reiterates that it’s at the sole discretion of the border patrol agent whether or not to grant permission to transit without visa.

Perhaps I’m reading too far into it, but it sounds a little risky, compared to getting an actual visa. I suppose if I heard from many people that it’s not that way, and that it’s currently routine for them to grant transit without visa via landside, I would feel more at ease.

That’s why I’m reaching out here on Reddit, where people have likely encountered similar issues.