(For a more formal report on this, please refer to Section 7.1 of my Ph.D. Thesis.)
This is a network showing the average daily influence on Twitter for some urban centres in the UK. It is based on a set of 70 million tweets posted within a 6-month window and geolocated in the UK.
Starting from London and going clockwise, the importance or influence of a location (node) decreases. The network is directed; nodeA → nodeB means that nodeA influences the content of nodeB.
A quick and easy observation is that London, Manchester and Liverpool are UK's most influential cities in terms of Twitter content on a daily basis.