Sherlock, this really was us three years ago. One rejection, and an offer from a fifth choice he no longer wanted to go to.
Nothing then came through till mid March, with two further rejections and one offer.
It was very hard, not least because these kids have often not faced rejection before. And we had not expected it. (DS was taking five A levels, was predicted A* in four of them, and had the equivalent on an AS in a European language. Economics is surprisingly brutal.)
Both Bath and Edinburgh will have lots of EU and international students who they will have to evaluate. It is more than possible that you will have to wait three or four more weeks.
Finance is different from economics, and Stockton is different from Durham. Depending on what he wants to do after graduation, there can be some advantage in graduating with a University of Durham degree. However it also needs to be somewhere he wants to live and a course he wants to take. Without knowing him my guess is that he might be better off approaching established Universities like Birmingham, York and Nottingham and seeing if they would entertain a late application.
But again, he ought to be an attractive candidate with an achieved A* in maths.
You only need one place,. no news is good news etc....hang on in there.