Look at the institute of fiscal studies website
www.ifs.org.uk/tools_and_resources/where_do_you_fit_in
It is not the finest tool but gives an approximation of what your income is compared to the rest of the country. What I despair of is people on 100k saying they are not high earners. I appreciate housing in the SE and other parts is ridiculously overpriced and actually overpriced pretty much everywhere but most people will never earn 100k or even close to it.
We are in top 10%, we had a few years being in top 5% but I retired early due to ill health when in my forties.
DH closest friends are people he met at Cambridge when reading for his PhD so they all have very well paid jobs. My friendship group consists of many academic librarians, I was one for 25 years they earn less than his friendship group but still decent money.
I studied income disparity and education attainment many years ago so read around that subject a lot. There will always be outliers, though social mobility still exists it’s even harder these days.
My siblings remain poor on NMW, I was the only one to attend University. It opened up a whole new world. Not everyone who gains a degree ends up in a well paid job though.