It's not as simple as winning back the north though. With Scotland out of the picture Labour needs to win back Southern England seats too for a majority.
For example the Medway seat (now Rochester ) is as much part of the "Red Wall" as Hartlepool, it just fell earlier:
There are similar post industrial seats along North Kent and the Solent with socially conservative, Brexit heavy electorates. Labour held these in the Blair years but wouldn't win them at the moment.
The problem with Rochester and Strood, and several other Kent constituencies is they may have a 'red wall' centre but are surrounded by a landscape of blue. In this case, the constituency includes the Hoo peninsula, most (but not all) is rural largely commuter land, Cuxton and Halling (commuter villages), Wainscott (comfortable middle class or retirement), new developments to the south of the constituency (with easy access to Chatham Station). The riverside development just north of Rochester Station is unlikely to be filled by those on the minimum wage, partly because the riverside views will have added at least £30k to the price. These and similar developments in the area will be occupied by those who have felt pressured to get on the housing ladder, used the Bank of mum and dad to get the deposit, can just about meet the mortgage payments, are DFLs ('Down From London') or from other high house price areas, aren't really interested in politics but are easy to scare into the blue corner with tales of Labour extremism that might affect their income/ mortgage/ job security (although it is probably safer under Labour). Labour needs to appeal to them. And a picture of a property in the constituency at the 2014 by-election with three St George's flags and a white van outside by Emily Thornberry did nothing to help. Who did she think used to vote Labour?
That the constituency had a UKIP MP after Mark Reckless, the sitting Conservative, resigned and won the resulting by-election under the Farage banner says something about the it.
The division of the county into constituencies doesn't help. The neighbouring constituency, held by the excellent Tracey Crouch, is Chatham and Aylesford. If you start from Chatham and go south there are a lot of dollops of green and commuter villages on the map before you get to Aylesford, the area is a house builders delight.
Areas such as parts of Thanet, Dover, parts of Swale are similar; core of potential Labour voters, but with a wide blue rim and Brexit voting. Not only does Labour look like wining them, I don't think Blair would either.