Gateshead is part of Greater Newcastle, just like places like Whitley Bay and even Sunderland, debatably.
Quite possibly the biggest load of horseshite I've ever read, and there have been some contenders I can tell you.
Sorry, been waiting to use that for a while - a lass at uni once asked "So is Sunderland in Greater Newcastle" and I quickly filed it away under "Suggestions likely to give a mackem a conniption fit."
I'm nicking that