John Major wasn't working class. I agree on Ramsay MacDonald but the others certainly were privileged enough to a point where I can not consider their background to be 'working class'. I am assuming you refer to their background, though, and not pro-working class policies.
Callaghan's background was hardly privileged, even if his class position was confused. It's mildly interesting to note that the reason he became such a strong Labour partisan (and all that led on from that) was a minor reform to service pensions (allowing widows to claim them, or something like that. I forget the details) introduced by the first MacDonald government.