"Ryanair are having significant problems with delivery of their 737s that are on order"
Although certainly an issue, think that was an excuse made up when Ryanair were slow to confirm that last years routes would return. Other UK airports have seen a Ryanair expansion.
"It really does seem there is a huge reluctance on behalf of other carriers to use Teesside"
When the mayor secured the Ryanair deal it was reported that there was a no competition deal preventing other low cost carriers from coming in for a period so we were never going to see Easyjet or Jet2 etc. Is this still the case?