Others have noted that this one can be a bit dry and "academic" (as an academic, I can assure you, this book is not academic, even if it is dry), but I think the problem is that it falls between two stools. I know very little about the politics of the time, and found those chapters absolutely impenetrable, which was a disappointment, because the chapters on the royal family made the republican in me want to throw up, in a bad way, not in the good, watch the car-crash kind of way, and I was holding out hope for the chapters about real people.
On the other hand, the social-political history chapters (where I had a firmer handle on who these people were) were almost embarrassingly bad. To take one example, Hattersley talks about 'Marx's Erfurt programme,' (page 222). Karl Marx: 1818-1883. Erfurt Program: 1891. Not even Marx was so domineering that he was writing party programs from the grave. That Hattersley was a Labour Party deputy, but has this understanding of the history of social democracy, might help to explain the Labour Party's performance during the 1980s. The chapter on the suffragettes was better than most, because focused so heavily on the Pankhursts, and thus assumes less knowledge from the readers. On the other hand, the suffrage movement was a lot bigger than the Pankhursts, and some of Hattersley's judgements are astonishing. His distaste for 'militancy' is particularly odd, since he suggests the suffrage movement would have been better off without it. How, exactly, women (or any disenfranchised people) were meant to get the vote without militancy is a puzzle to me.
The chapters on literature reveal only Hattersley's appalling preferences. The whole thing could just be summed up as 'Virginia Woolf was wrong about everything. Arnold Bennett will live forever, like his characters.' The concluding chapters on newspapers could surely only interest professionals.
Finally, Hattersley is tediously oppositional to "his" side. Any Labour heroes get cut down to size. The suffrage movement was mostly cranks. Churchill, by contrast, comes out reasonably well, and the Liberal leaders are clearly the heroes of the story. Those are perfectly reasonable positions to take, if they are argued for. Here, it's just stated, often quite snarkily. You think this guy was a hero of the working classes? Well, he was an adulterer! Take that! I mean, really?
So, if you know a lot about something, you'll find Hattersley's chapters filled with errors and misjudgements. If you don't know anything about something, you'll find his chapters on that topic incomprehensible. That's a shame. (It's possible, of course, that the chapters about the royals and the politicians are impeccably true and judicious, and I just don't know enough about the era to grasp that. I hope that's true).
Nonetheless, there's good stuff here, and since I picked it up for a couple of dollars, I'm not complaining too much.