Look at leaders of the Labour party since the sixties:
Harold Wilson: 1963-1976
James Callaghan: 1976-80
Michael Foot: 1980-83
Neil Kinnock: 1983-92
John Smith: 1992-94
Tony Blair: 1994-2007
Gordon Brown: 2007-10
Ed Miliband: 2010-15
Jeremy Corbyn: 2015-present
What this tells us is that Labour is naturally a left-wing, social engineering, highly statist party. A party that that will never naturally be a centrist party. (Going back before the sixties doesn’t change my opinion on this either.)
It takes a tremendous effort to drag the party to the centre. Tony Blair managed it with what was virtually an internal social revolution within the party. But it didn’t hold. Despite delivering the most sustained period of electoral success the party had ever seen, the party got fed up of centrism, forced Blair out, and once he was gone the whole ‘Third Way’ project quickly unravelled, with Brown taking it somewhat leftward, then Milliband further leftward, and then Corbyn back into loony left territory. The party decided that electoral success wasn’t as important as maintaining the rage.
It should also be noted that the reason Blair and Mandelson possessed the energy and strength of will to try to transform Labour was because they believed that they could deliver leftist aims under the guise of an apparently centrist party which had electoral appeal. To a large extent, they succeeded in this, winning multiple elections by masquerading as a centrist party, whilst quietly changing the country and taking it leftwards behind the scenes (on immigration, the EU, the Supreme Court, etc.). It is doubtful whether the New Labour people would ever have put so much effort in had they not believed that they would be able to enact structural changes that greatly benefited the left.
We’ve never seen any great desire on the part of Labour (either the members or the MPs) to become a centrist party because centrism what they believe in. At most we have seen the occasional desire on the part of a few Labourites to become a centrist party for the sake of winning elections. But even that is not a desire to be a sincere centrist government delivering centrist policies, but to be, as I claimed above, a government in power who can then force leftist policies onto the public, either openly or surreptitiously.
So history tells us that the odds are greatly against Labour becoming a centrist party again. Centrism is alien to Labour, whereas leftism is in its DNA. It takes a tremendous effort to drag it away from the left. So even if we momentarily put aside what the party is like now, and the context it finds itself in – I’ll discuss such things in another post soon – past experience tells us that a move to the centre is unlikely.