This doesn't surprise me. The portrayal of the Thatcherite times of my youth by the left-wing establishment has long been ridiculous. It's amusing that it takes such statistics to give the lie to their distortion of history. It's more than amusing that, having acknowledged without thinking that things were (in their terms) better in the Thatcher era, they will now propose more of everything that made matters "worse".
Inequality is not a bug, it's a feature. Like a young man I once knew whose whole career was propelled by one ride in a Ferrari, young people need fuel for ambition. They need to aspire to things that they can't have if they don't make an effort with their education and career. People are different. They don't all have to want the same things. Maybe other youngsters would be inspired to create wealth for the chance it could bring to cure AIDS or cancer. Maybe they just want financial independence to enjoy quiet leisure. The fact remains that if the equality Labour bangs on about so much were actually ever to be achieved, few except saints and sadists would put in much effort.
Every government intervention to create equality will make things "worse". Consider the extreme level of "intervention" adopted in Soviet times. It resulted in huge inequalities between the lifestyle of shop floor or agricultural workers and the Party bosses. Arguably they were far greater than in capitalist countries, where the biggest bosses of the most powerful companies did not enjoy anything like such power over their fellow men.
My driver in post-communist Poland was the son of the General Director of a State Enterprise. They used to fly to their family holidays on the Black Sea in his personal helicopter. Worse, he was offered a place at medical school on the basis of his father's status. Thankfully, he was responsible enough to decline, knowing he was not smart enough. Every time I met a Polish doctor of a certain age, I wondered how responsible he had been when offered such a chance. Every time I hear a Labour politician propose to force universities to take account of the class background of applicants, I remember that story.
All this was happening while at the same time production was being driven into the ground because, in the words of the proverb of those times, for the ordinary worker;
"Standing up or lying down it's still five zloties an hour"
Why has inequality increased since the 1970s in Britain? Because Labour destroyed (and the Conservatives did not stop them) the grammar schools. If you are born today into the sort of community where I grew up, your only educational option (unless your family is already very wealthy) is a shabby comprehensive school with an appalling academic record and a bad attitude to the very idea of achievement. If you dare to aspire academically, the negative peer pressure from a proudly ignorant community will be reinforced, rather than balanced, by left-wing teaching staff. They will sneer at your "elitism". Your time will be wasted on political indoctrination, and on staff dealing with kids who should never be in the same classroom with you.
If you are black, female or gay you will be told that you are doomed by racism, male chauvinism and homophobia (all of which exist, and none of which have ever prevented anyone from achieving who had talent and actually made an effort). What effect do you expect such teachings to have? Would any sports coach tell his players they have no chance? So, if you are a good boy or girl and believe your teachers, you will actually do less well than if you rebel.
You may well be better off leaving school early and starting a business, provided you are not stupid enough to grow it to the point where it creates employment, thus attracting the attention of the regulators. How many of our glut of cardboard graduates earn enough more than non-graduates to justify their investment? Education doesn't increase equality of opportunity across society as a whole unless, paradoxically perhaps, it gives opportunities to individuals to rise above their peers, whether financially or otherwise.
A rational society strives for quality, not equality. It strives to give those who have talent the maximum incentive to deploy it. A vibrant society that efficiently harnesses the energies of its most talented members is a richer society overall. The creations of the creative and the output of the industrious may fill their bank accounts more than others, but their effort benefits all. The corollary of that is that the idleness of others, costs everyone. A rational society therefore incentivises effort and never rewards idleness. In pursuit of the chimera of "equality" Britain has adopted precisely the opposite approach. Now we can see that, even in its own terms, it doesn't work.