In 1974 it merged with part of Durham Constabulary to form Northumbria Police .
Northumberland Constabulary absorbed Berwick - upon - Tweed Borough Police in 1921 and Newcastle upon Tyne Borough Police and Tynemouth Borough Police in the late 1960s , more than doubling its strength .
In 1974 Northumberland Constabulary merged with part of Durham Constabulary to form Northumbria Police .
Northumberland Constabulary absorbed Berwick - upon - Tweed Borough Police in 1921 and Newcastle upon Tyne Borough Police and Tynemouth Borough Police in the late 1960s , more than doubling its strength .