Gladstone, sort of.
His Chancellor, Harcourt, brought in the first of the Death Duties which went on to prevent the rich passing all their vast estates on to their kids (oldest son usually) which was an awful system imho.
Gladstone didn't like it, though.
Lloyd George, again as Chancellor, brought in the Old Age Pension which was desperately needed. He was PM later.
Then before anyone accuses me of being a leftie, Thatcher for smashing stupid unions.