There was that little village in Armorica which pissed them off so.
Let's say the Romans felt it wasn't worth their efforts to conquer Britain, maybe they never saw it as more than a backwater?
Would Britain have remained an Iron Age community until sometime into the middle ages?
I heard that in southern britian they were already forming cities and were transationing into a romanish techonlgy by the second invasionTo give your question more consideration: Even without legions invading and occupying, the southern parts of Britain are going to strongly influenced by Roman society via commerce, the occasional piracy and retaliation, and eventually by Christian missionaries. Further, the Germanic tribes will likely still enact their invasion of Britain from the late 4th century on (if not earlier), those Jutes, Angles, and Saxons.