(11 Feb 2015, 8:02 pm)MarcTheA4 wrote Bit of a silly question - is there any specific reason the 'E' services go E1, E2 and then E6? And no E3, E4 etc?

Just curious.

It's a long-time survival of competition years ago between Busways and a firm called Catch-a-Bus, who were based at East Boldon. They mainly operated local services in South Shields but also had a route between South Shields and Sunderland, using route number 6. Busways' retaliation was numbered E6 to match the Catch-a-Bus number.
This would be in the 1989-1993 period if I remember correctly. There was also an E3 for a short time. If I can find the details of this route anywhere, I'll post them tomorrow.
Hope this helps,
Chris