I haven't read every single edition of the Daily Mail since 1939 or even since 1960, so I do not personally know whether the paper has ever apologised for its support of 1930s fascism. However, why should they? Lord Beaverbrook thought it right at the time, and the editor just had to follow his lead (or be out of a job during a recession) so any apology should be from Lord Beaverbrook himself, not subsequent editors of the newspaper.
I knew a Radio producer who interviewed Diana Moseley, who, my friend said, had the most charisma of anyone they had ever interviewed, including the royals, intellectuals and others. By the end of the interview, my friend said, they felt almost hypnotised into supporting fascism. (Until they left the studio, went home and rationalised everything.)
The Daily Mail was always aimed at lower middle-class women. Even today's readership is said to be at more than 50% female.
It was a much better paper under Sir David English. It is true that it has dumbed down, but so has much else in the UK. Now, particularly online, they have oodles of ridiculous and irritating stories about zelebs, presumably to compete with The Sun and The Star for online clicks. And I particularly hate those double-page spreaRAB of 6 women wearing almost identical dresses with boring stories to tell about their (enter issues here).
To be honest, I don't actually buy newspapers any more. The DM is 2.50 euros here in Greece and others are even more expensive. It is free to read it (and any other paper) online. I've always liked The Independent and rather like The Telegraph lately, so I'm not particularly confined to the DM, but do feel there are far worse papers to slag off.