This is very good as usual by @andrewrawnsley but you could query one implicit assumption. Were Blair, Clinton and Schroeder really social democrats?
There has been an almost universal consensus in Europe since 1945 favouring "regulated market economy with good public services and decent welfare protection", so the distinction between social and christian democrats wasn't about whether or not they wanted this.
It was more nuanced than that, no? About where you drew the line between market and state? And surely the gang of 1998 drew it closer to where liberals would traditionally have drawn it, than to where social democrats would traditionally have drawn it?
To that extent, couldn't you argue that it is as much a case of social democrat parties abandoning their voters, as it is of their voters abandoning the parties?
Or to put it another way: if the "historical voting coalition" of social democratic parties was "the working class and middle-class liberals", didn't Blair, Clinton and Schroeder instinctively identify more with the latter than the former?
Perhaps that is inevitable for a generation of leaders who came to politics from glittering university careers rather than trade union backgrounds.
Now, it is true that workers often did very well during the Great Moderation overseen by these leaders, but in retrospect that achievement seems to have been at least in part based on some fairly shaky debt-fuelled ground.
And Schroeder's impact on German workers was NOT unambiguously positive, to make an obvious point.
So IMO social democrats need to do some soul-searching. But the good news is that there is a huge agenda awaiting them should they wish to adopt it: social housing, job precarity..
And they really do have to break from the rhetoric of "we have to downsize the state/deregulate/undercut protections" in order to stay competitive in a globalised world. That is an argument the right should and does make. It's not a left-wing argument.
The premise is IMO wrong and Scandinavia which has been open since the 19th century is the proof of that.
But if people believe the argument then a lot of them will quite understandably conclude that globalization is a bad thing, and who could blame them?
Instead the left should be arguing strongly for international cooperation to prevent regulatory races to the bottom. There is clearly a big potential role for the EU here, and Brexit will maybe be helpful in clarifying the issues for everyone.
How many times have I heard French people saying that they are in favour of Europe, but that it needs to become "plus social".
IMO they're right.