The sad truth is that when shipbuilding, the majority of ICI and the steelworks were taken outside and shot, the airport (DTV, Teesside or Middleton St George) was as good as finished. The airport relied on the business travel that those industries supplied. When the industries departed in the 90s, 00's, the local community could not support the quite substantial charter market that had built up. In the main they have naffed off leaving a few niche routes.
After the demise of heavy industry the Teesside area has pushed for the technology market to replace the manual labour it employed before. All well and good but that business is mainly done online. Far fewer bums on seats for business, mainly lower wages and fewer jobs for the bucket and spade runs.
Those that have money are far likely to choose not to go to Alicante (unless they have a house there) they can not get to London by air so routing through NCL or MAN are the only realistic options to get away to where they want to go by air. KLM offer an invaluable service to route through Schipol, but for how long?
It saddens me but it aint looking good