The University of Edinburgh Msc. Informatics 2021 ApplicationsWatch
All universities have been talking about "record number of applicants" this cycle, plus a lot of students must have deferred from last year, so they're operating with very few spots. I really don't know on what basis they reject students, and it would be really helpful if they could include more than a generic letter.
But, the unis you have got into are great! I'm not from the UK but I've only heard good things about QMUL and St Andrews - it's up there with Edinburgh and Imperial. Don't take the rejection to heart, you're going to do so much better at a place that has done your application justice and really wants you there.
Need more help on going postgrad?