What evidence are we actually referring to? Is it possible to be specific? Having studied this topic due to my genuine local interest there are plenty of “legends” which support a more tumultuous co existence and frankly I don’t think anyone can definitively give credibility to either position.
Sure yeah.
The continuity of settlement in Lincoln, including its church building (site of present St Paul-in-the-Bail), expanded in the 6th century and probably demolished and rebuilt as the Anglo-Saxons took over the British church. This is further supported the lack of AS cremation cemeteries around Lincoln, showing a stretch of land where Anglo-Saxon culture can't be demonstrated until the later 6th century, surrounded by areas where AS were clearly present. In these cemetery areas, high-status Anglo-Saxon metalwork is found which is absent from the area around Lincoln, contrasting with York, Leicester, Ancaster and Caistor in Norfolk where AS cemeteries and metalwork are found right by the Roman walls. There is also the presence of British style "type I" broaches in Lincolnshire which are absent from the AS territories, but present in the British controlled regions further north and west, there is also evidence for their local production. This is mirrored by the presence of British-type hanging bowls, which appear all over Lincolnshire (indicating adoption by local AS populations) but rarely anywhere else Anglo-Saxon. The distribution of these finds suggests a degree of acculturation by British elites in conquered areas, and a certain adoption of British mores by AS individuals.
In addition there are the linguistic arguments, the one possible (Cretta) and one definite (Caedbaed) Celtic name in the kinglist of Lindsey (and it's a very short list if we ignore fictional characters). We also have the British names Vasso and Turch attested in AS placenames near Lincoln, showing British-named individuals were important in contemporary Lindsey society, we don't get that at all in East Anglia or Kent, where any Celtic toponyms are geographical. And the name Lindsey itself which is best explained as a wholly Celtic name Lind-
issi, the men of *
Lindes (Lincoln)
, which requires a 5th-6th century Celtic polity to have been coined. This is unlike Kent, whose attested forms only require knowledge of the Latin name existing when the AS arrived. The name underwent a rational development in Welsh to Linnuis, where it is mentioned in sources that refer to Linnuis men as Britons. There is also the name of Lissingleys, which probably contains Welsh "
Llys",
royal court.
It is also worth mentioning the legend of Havelok, first attested in the 12th century, which mentions Orwain "the sister of the king of Lincoln and Lindesi" who is "a Briton".
This strongly suggests, as an ensemble, a long period of stable coexistence between a British polity and AS polities, which, despite the possibility of violence at times, generally mixed together and formed an alliance. These polities merged in the late 6th century, with the AS element dominant culturally, but with elements of the British elite co-opted, and a degree of mutual understanding which allowed the continuation of Christianity in Lincoln. It is likely these 6th century polities were often in conflict with other groups, both AS and British, and the traditions of battles recorded later could easily apply to mixed ethnicity armies on both sides.
There is some amazing work on this by
Caitlin Green, which you should enjoy!