As someone who lives in a suburb of London (Croydon) that has a city centre bigger than many cities, I think there's a lot of desire for reducing concentration even in parts of London. My local council in fact has kept trying to drum up support for getting city status for decades, and I think some would even like to "break free" of London entirely.
Part of the problem is that London is a bit in the same situation as the old "every road leads to Rome" saying, and amongst many types of businesses in London, anything but Zone 1 or maybe zone 2 is never even considered when deciding where to set up offices as a result.
So even a lot of London suburbs remain underdeveloped and ignored compared to what their population size would justify because we have the behemoth next door sucking everything in.
With the new-ish London rail projects that are increasingly aimed at cutting through central London, as well as the new orbital overground projects (one completed, another one further out in planning stages AFAIK) there'd be lots of opportunities to break the stranglehold of central London by making more of the smaller centres at the edges of London more attractive by making them more accessible.
I hope we'll see more projects like that - making bypassing (central) London easier both on a local level but also nationally.
I think that will actually have far greater long term impact on the UK than devolving more powers to regions (though I'm all for that as well).
The problem is that fixing this would be a long game: To get maximal effect you'd need to upgrade many routes to handle more frequent, faster trains, and increase train frequencies on many of those routes at potentially significant short term losses and commit to continue running them for a decade or more before there'd be much chance in changing peoples decisions about where to place their companies and where to live and work.