Flavia Caesariensis

Following the Roman conquest, Britain was administered as a single province from Camulodunum (Colchester) and then Londinium (London) until the Severan Reforms following the revolt of its governor Clodius Albinus.

At some point after the territory was retaken by Constantius Chlorus in AD 296, the Diocese of the Britains (with its vicar at Londinium) was formed and made a part of Prefecture of Gaul.

[5][6][7] The placement and capitals of these late British provinces are uncertain, although the Notitia Dignitatum lists the governor (praeses) of Flavia being of equestrian rank, making it unlikely to have been based in Londinium.[why?]

[9] Describing the metropolitan sees of the early British church established by SS Fagan and "Duvian", Gerald of Wales placed Flavia around London, extending into Mercia.

Birley has argued that Maxima and Flavia originally consisted of a single province, which received the name Britannia Caesariensis as a mark of favour for support against the rebel Allectus in 296.

Roman Britain around AD 410 , without speculative provincial borders.
The traditional arrangement of the late Roman provinces after Camden , [ 2 ] placing Flavia in central England. On the basis of modern archaeology, it's known that at least Corinium was part of Britannia I .
Another possible arrangement of the late Roman provinces, with more northerly borders for Flavia