Answering this question and apologies to OP if getting too far off topic…
Anecdotally, our local privates send a few kids every year, primarily to St Andrews since it is more “US education system friendly”. My D’s high school (class size about 115) sends a kid to UK on average every other year.
My D had St Andrews high on her list until she decided on a pre-med track. Thanks to one of my very uninformed and very naïve early posts on CC, we figured out that was not an option. (She kept McGill on her list for a while (realistic international option for pre-med) but that was ruled out due to covid restrictions at that time.)