Well, it seems I have effectively sidetracked the thread.

Oh well .... in for a penny ...
It is true that at the time that Angles, Saxons, Jutes, and Frisians began settling in the British Isles (late 5th and early 6th centuries) they spoke their own languages. But they were
very closely related. So close that they could understand one another in much the same way that Danes and Norwegians can today. But be that as it may, in those earliest years, nobody talked about Anglo-Saxons. Apparently this nomenclature first appears (in writing at least) in the 8th century, and is itself indicative of the emergence of an ethnic identity among the various groups/kingdoms. No doubt in part because at that time there was an invasion of those pesky Danes (My ancestors

) happening which necessitated the making of alliances. So Alfred's Wessex made an alliance with Mercia, which gave Alfred the clout to conclude a peace treaty with Guthrum and the Danes who had settled in Northumbria and East Anglia (what came to be called the Danelaw). Alfred encouraged the development of an English identity in the non Danish region under his control, even encouraging that things be written down in English. This was somewhat unusual in a Christian Kingdom, as Latin was the language in which things were normally written. The English language and identity continued to emerge in subsequent centuries. Living in proximity to and trading with the Danish settlers and their descendants had a tangible influence on the ever changing language and culture. (If you you are a "husband" who has "skill" cutting "cake" with a "knife", you can thank a Dane.

) Alfred's descendants reconquered the Danish territories, and subdued the regional aspirations of the rest of the Anglo Saxon kingdoms, with all of them eventually came under the rule of King Edgar the first who reigned from 959 until 975. Then those pesky Danes came back under the King of Denmark Sweyn Forkbeard (1015), and after his death, under his son Cnut the Great (1016) when King Æthelred the Unready lost the whole of his kingdom to the Danes. Æthelred's kingdom had pretty much the same boundaries of what we consider England today (excluding of course Wales, Scotland, and Northern Ireland) and this is the Kingdom that Cnut conquered and ruled. However, Cnut did not impose the Danish language or laws in England. He was referred to as the King of Denmark, England, Norway, and parts of Sweden. The point being that he differentiated between his English kingdom, and his Scandinavian ones. He reigned until his death in 1035, after which the kingdom of England went through a period of upheaval over questions of succession. And one of those with a claim to the throne was William the Bastard, duke of Normandy. His claim was to the throne of all of England, and was based upon his assertion that his distant cousin Edward the Confessor (Who was king od England, and with whom William they shared Æthelred as a common ancestor) had promised it to him. Godwin, earl of Wessex, a powerful man during Cnut's reign who was a relative of Cnut's by marriage set the stage for his son, Harold Godwinson, to be crowned King of England. And this of course ticked William off, and the rest is history. But by the time of the Battle of Hastings, the Kingdom being contested was geographically the England we know, and was called England. The language spoken throughout the kingdom was called English. The regional dialects then, like today were quite different, but it was called English. The old kingdoms of Wessex, Northumbria, Kent, etc. were now earldoms within a larger England.
Here is an interesting series of youtubes if you are interested in such things. It is about the development of English as a language, but there is a good deal in it about the development of the English identity as well. Part three is where we get into Alfred and the Danes.
https://www.youtube.com/watch?v=7UG6vHXArlk
https://www.youtube.com/watch?v=y3lV7_d7m-I
https://www.youtube.com/watch?v=DuyEXotPRxM
https://www.youtube.com/watch?v=FNZVSbQcpCI
https://www.youtube.com/watch?v=hZcjkIXLZCw
https://www.youtube.com/watch?v=UZ5UUOtkAX0
https://www.youtube.com/watch?v=h5GH2rho-xo