Just having a remember moment !
When each Northern General / Go ahead Northern, depot had their own service number batch -----
Chester le st depot were 700s (721,22 etc)
Gateshead (Sunderland Rd) were double numbers (20s and 50s)
Winlaton and High Spen Depots...600s
Wallsend and Percy Main Depots...300s
Park Lane , Murton,and Philadelphia Depots were 100s
South Shields and Jarrow Depots....500s
Washington Depot were also 100s and the mini links were colours, Orange Route etc.
Anybody correct me or add to this.... thanks