Who is really powerful in the British Labour party? Who wins votes, decides policies, commands budgets, doles out jobs? Who knows how to run something?

I tell you the answer.It is people such as Richard Leese, Nick Forbes, Judith Blake, Albert Bore, Julie Dore, Peter Soulsby, Jules Pipe and Robin Wales. You have probably never heard of them, because you think important politics happens only in Westminster. The above are Labour leaders, half of them elected mayors, in Manchester, Newcastle, Leeds, Birmingham, Sheffield, Leicester, Hackney and Newham.

Of these, at least half would certainly knock spots off the current leadership frontrunners. In American politics they would be hot favourites. In Britain they are excluded from running.

Labour’s tribulations are, of course, another curse of Blair, who dismantled Labour’s baroque constitution, ended the union rotten boroughs and introduced one member, one vote; who went to America in 1993 and fell in love with Bill Clinton and charisma politics. He destroyed Labour as a coalition of interests and institutions, and bequeathed an atomised democracy. For good measure, the Tories did the same.

I find it unbelievable that, in going down the same route as the Tories, Labour did not take elementary anti-maverick precautions. These included a knock-out contest among MPs to select two finalists and a three-month membership qualification for voting. Even so, it would be odd if tens of thousands of crypto-Tories really have signed up to get Jeremy Corbyn chosen. Would thousands of socialists have joined the Tory party to vote for the hated Thatcher?

Half the Corbyn supporters I have met see him simply as that modern political poltergeist, a man who can “authenticate authenticity”. He is on that emerging spectrum of political humanity that embraces Alex Salmond, Nigel Farage, Boris Johnson and Donald Trump. They pass the barbecue test, the elevator test, the person you would most like to meet. To be “not a politician” is becoming a key qualification for a political career.

I watched the recent Newsnight interview with Yvette Cooper in amazement. How many people was she out to alienate? Renationalisation was about switching “from one group of white middle-aged men” to another “group of white middle-aged men”. Infrastructure was about “boys’ toys”. The economy was about “childcare”. Her one favoured group, over and again, was “working mums”. Bang went all white men, all women commuters (and engineers), all stay-at-home mothers.

Public aversion to national politics on both sides of the Atlantic is accepted as a function of the decline of financial self-interest in elections. American social psychologists such as Jonathan Haidt and Daniel Kahneman discern that people now vote comfortable, tribal, secure, even philanthropic, rather than pocket book. Trust and likability really matter. As they said in Primary Colours: “Just smile and feel their pain.”

The so-called Blair project of 1997 was a rebranding of the party not just as “new” Labour but as presidential Labour. Blair ran against his old party, as David Cameron did against his in 2005. They ran against dinosaur Labour and nasty Tory, and in both cases it worked.

The unresolved question was how far this dismantling of parties as closed enclaves should extend to the leadership. Both Labour and Conservative went for one member one vote, tweaking the process to avoid a wild card getting through. The Tories got into such a mess that they had five leaders in eight years. But both parties kept the requirement that the leader be an MP.

If Corbyn is chosen as leader, it will indicate how far party support in the country will have moved away from anything to do with the party at Westminster. The latter will be seen as an Oxbridge clique of the sort that led Labour after 1945, but without the working-class leavening of figures who had advanced mostly through the trade unions. The Attlees, Daltons and Gaitksells were popularised by Bevins, Shinwells and Bevans.

If Labour wants to progress it must find new leadership blood and open its primaries to all comers. If the winner is not an MP, he or she can become one. The leadership was split in 1931, when Arthur Henderson led in the country, albeit briefly, and George Lansbury in parliament. In 1963 Lord Home became Tory leader after Macmillan’s resignation. He was subsequently found a safe seat.

Candidates for the London mayoralty are not confined to the London assembly. Labour’s London line-up is, if anything, more impressive than for the party leadership. Direct election, with the presence of mavericks such as Ken Livingstone, offers the party and the electorate a proper choice. If it fouls up, blame democracy.

Labour is favourite to win next year in London, which will make one of the candidates – Tessa Jowell, Sadiq Khan or the rest – the most powerful Labour figure in the land. It is absurd that, in order to progress to party leader, that person should first have to become an MP, as has the Tory, Boris Johnson. It is like requiring a policeman to become a freemason before being chief constable. Such “pre-entry closed shops” should be out of date in a modern democracy.

Thatcher used to say her proudest creation was a Labour party that could elect Blair as its leader

A significant moment in the downfall of Ed Miliband came in spring of last year after George Osborne’s “northern powerhouse” speech. Manchester’s boss, Richard Leese, was in the middle of negotiating with Osborne on his city’s devolution plan. It involved a major restructuring of public administration, possibly across all of local government. Miliband’s office wanted Leese to rubbish Osborne’s speech. The reply was reputedly unquotable in a family newspaper. Who did these snivelling Westminster teenagers think they were addressing?

Osborne’s conversion to civic devolution may be untested. But it was an opportunity the Labour leadership should have seized with open arms. It was pushing control and resources to precisely the electoral bases on which Labour had to build, to the big northern cities and to London. It was a gift to the party’s future. Miliband and his Westminster colleagues simply did not get the point.

Thatcher used to say her proudest creation was a Labour party that could elect Blair as its leader. Who knows, history may repeat itself. Osborne’s proudest boast could be a Labour leader from the ranks of his newly elected mayors. Will Labour let it happen?