I notice there is a tender out for services 351 and 359, due to start on 3rd September. I'm assuming the 351 is a direct replacement for the 51, and the 359 will be a Whitley Bay to Backworth service.
There is also a tender out for service 335 - not sure if this is because of a change to route, or GCT have been stripped of the contract (wouldn't be surprised as the reliability is awful)
Nexus Tenders - September 2023 (North Tyneside)