More on the Anglians: Those soldiers belong to the Anglian Regiment, a consolidation of some county regiments carried out as part of the downsizing of British forces following the end of conscription in 1960.
It should not be deduced that the good people of Luton are parochial in their loyalties. If you watch the video, you will see that many of those welcoming the troops are waving their national flag — the red cross of St. George, which is the national flag of England. These are fully patriotic citizens!