I discuss Wilkinson and Pickett's misrepresentation of Alexis de Tocqueville in chapter 9 of The Spirit Level Delusion. To imply, as they do, that Tocqueville was an early socialist is laughable (you can read what he thought of socialism here).
There is one thing to add regarding Tocqueville's admiration of the 'equality of conditions' enjoyed in 1830s America. Anyone who has read Tocqueville's work (or, indeed, understands 1830s America) will be aware that he was referring to what we would today call equality of opportunity or equality of status. He certainly was not talking about equality as defined by Wilkinson and Pickett, ie. equality of outcome.
'Equality of conditions' is a somewhat ambiguous phrase which, as Hugh Brogan explains in his biography of Tocqueville, relies on a mistranslation:
Equality of status, or in AT's French, egalite des conditions. This is usually translated as 'equality of conditions', but this is misleading since nowadays it seems to imply economic equality, which AT knew perfectly well did not exist any longer in America, if it ever had...
In context it is perfectly clear what AT was concerned with, but not everyone has always remembered the context.
'Alexis de Tocqueville: Prophet of democracy in the age of revolution', Hugh Brogan; p. 275