There appears to be a lot of anecdotal evidence available online which imply that Heathrow is the worst UK international airport to enter the UK from, in terms of removals and terrible immigration experiences and that Manchester is better.
Articles like Heathrow’s Immigration Detention Centre is 'Among Worst' in the UK and London Mayor: Heathrow Airport Is Giving People 'A Terrible Impression Of The UK', and Manchester Airport soars over Gatwick and Heathrow to be named best in UK are among many suggesting so.
I read this
The Home Office produces statistics that inform us that approximately 1 passenger out of 2,200 arriving from the US will be removed at port from Will US boyfriend have issue visiting me in UK for 3 months? which provides data to be able to make some conclusions.
Is there data available to support the Manchester vs Heathrow assertion that someone can point me to? I am focused on the immigration experience (like removals, percent of secondary screening, time spent on landing interview etc), not the other stuff like delays, available facilities, parking, dining, etc