(12 Sep 2013, 7:34 pm)aureolin wrote Washington is ran by Sunderland City Council, in a Newcastle postcode area, yet the 'city line' of your address is officially County Durham.
Birtley is similar. Ran by Gateshead Council has a 0191 4xx xxxx phone number, classed as Co Durham and if you need post, you have to go to Chester sorting office.