Rattus rattus bone remains that date back to the Norman Period have been discovered in Britain.
From the en.wikipedia.org
Rattus rattus populations were common in Great Britain, but began to decline after the introduction of the brown rat in the eighteenth century.
From the en.wikipedia.org
Although predators like R. rattus are often a threat to native species on islands, there is evidence that R. rattus is becoming endangered in Great Britain.