The schooling comparisons are totally misleading. Of course the best private schools in Dubai perform better than the average state schools in the UK - it’s a totally different set of pupils attending them. How many dysfunctional kids from broken homes are attending private schools in Dubai? The average Dubai expat child has well-educated parents who are probably also above-average in intelligence hence why they’ve been recruited to work over there.
From my experience over in Dubai, JESS was a very good school with absolutely outstanding facilities. In terms of the actual standard of education it was similar to a very good UK state school. Interestingly, if you look at the UK you might be surprised to find the famous schools such as Eton, way behind on the results table. Cardiff Sixth Form College has the best A-level results, and that’s with your bog-standard average Welsh pupils.