Fishingeagle, what a pity. I had been rooting for your DS. He sounds both sensible and gifted. I hope he makes the grades required by Edinburgh.
Something needs to change. DS went through this almost a decade ago waiting until the March deadline to hear from LSE, Warwick and UCL despite a 4xA*prediction. At the time it felt as if he was unlucky, and some posters here were pretty blunt in suggesting that he himself had major shortcomings, otherwise it would not have happened.
But happen it did, and it was awful. Now it is worse. Many many more are affected, and the wait is longer. Oxbridge and medicine are allowed a early deadline because of the demand for places. Yet LSE etc often have a higher number of applicants per place (Oxford and Cambridge applicants are reduced because you can only apply to one, not both.) They also have a lower “yield” in that strong applicants are likely to get an Oxbridge offer as well and accept that, making predictions more difficult. Add in the fact LSE is small and does not want to go above numbers and you have a real problem.
I think the solution on very popular courses might be to give home students the early deadline. They will mainly be applying to Oxbridge anyway, so no great problem. Post Brexit there should not be an issue giving home students a different deadline from overseas students and operating an informal quota. Home students are then accepted, rejected or put on a wait list at about the same time as Oxbridge. Overseas students are processed after the January deadline. (Many will be applying for courses in several different countries.) If some of those on the wait list are better than the last accepted overseas student they can be promoted from the waitlist. (Medical schools also offer waitlists.)
One idea. Others may have better ideas. With increases in contextualisation and the increase in demand from overseas the problem is likely to get worse. 17 year olds should not be put through this, and it is likely to be more difficult for those from disadvantaged backgrounds. A solution needs to be found.