Well as mentioned above, the event was started by Brendan Foster (a local to the area) and one of the first large participation races in the UK. From memory it started off as couple of thousand but rapidly grew to tens of thousands. Just checked and the first event already attracted 11k runners!
Not sure about the first couple of years but after that it has been shown live every year on the BBC. This and the London Marathon are the big 2 which get massive coverage. The show lasts about 3 hours & they even show the highlights again later in the day! Think it appeals to them as it has high quality at the front plus mass participation and charity interest
I ran it in 1987. Went out in Newcastle the night before and it was just a normal night. Looked out of the hotel room in the morning and the whole city was transformed. Hundreds of people in running gear were streaming along the streets in every from every direction. The whole place was buzzing with an amazing atmosphere
The race is always massively oversubscribed but they used to always advertise first in the local papers along with an application form. As a result there are always a lot of local runners and following support.
The course although slightly dropping in elevation is not quite as fast as you would think. There are several miles where there is a gradual rise and you lose all this going down a hill just a couple of hundred yards long near the end