From my understanding, the Romans conquered modern-day England and Wales, which was inhabited by Celts at the time. I am aware that there was some cultural and linguistic merging between Latin and the Brittonic tongues of the British Iron Age, leaving many Romance influences on the native languages of Britain before the Anglo-Saxons migrated onto the island and bringing Old English. So my question is, do we have any evidence of Latin influences on Brittonic tongues having worked their way into Old English, before the Normans invaded in 1066 and bringing their version of Old French?
It's not very clear what you are asking. There is certainly Roman influence on Old English, in words like copper, wine, dish, linen - early loan words from Latin. There is also Roman influence on Brittonic languages. But as you note, the English were not in England until after the Romans left. So are you asking whether the Latin loanwords in Brittonic were subsequently loaned to Old English?