Gifted and talented, what a misnomer!
"talented" used to mean in the top 10% in particular subject, could be anything, knitting, roller blading, anything.
"gifted" used to mean either in the top 10% of more than one subject, eg knitting AND roller blading, or ( depending on the school or council policy) being in the top 10% of a core subject, English maths or science.
The cohort you had to be in the top 10% of was normally your year group in that school, so in other words, when I taught in a school for children with learning difficulties, all of whom were in the lowest 5% of the general population, the top 10% of each year group was G and T.
In other words, it meant nothing in terms of the general population. In a class of wheel chair using children, the ones who could get out and crawl on all fours were "talented" in PE, etc.
It was a requirement of a school to show that they had identified their most able students and were offering them something a bit extra.
These things go in cycles, however. "differentiation" fell out of favour on the grounds that it doesn't give everybody the same opportunity, demonstrates lower expectations for some students, etc.
The next time differentiation came round, G and T was no longer the preferred term. Now its "maggots". Maggots are the "More Able, Gifted and Talented" and represent the top 20-25 % in every year group.
This too will pass...