If anything, this underestimates how long it took to reverse decline in northern English cities. The Blair governments were able to build on local, national and EU programmes already in place/already achieving impact. Some dated back to early 1980s. https://www.theguardian.com/commentisfree/2020/dec/27/the-tories-are-out-of-excuses-now-and-must-start-work-on-levelling-up-britain

Assuming the commitment to levelling up is serious (it will have to be if the Tories want to retain the seats that provide their majority) the hardest part will be the decade or more of high-profile, potentially costly, initiatives that appear to have little or no impact.

Reversing local economic decline and bringing about related, sustained improvements in housing conditions, income levels, educational attainment, health outcomes etc will take a generation or more. That’s probably the key lesson from past urban regeneration programmes.

And part of that long-term approach includes sticking with things that look as though they represent poor value for money in the short-term, but will pay off in the long-term, or with “white elephants” whose role in regeneration may only become clear 15-20 years later.