Imply/infer is branded on to my skin, Jim. Fifteen year old VE's English Language O-Level had the question "Construct a sentence using the verbs 'imply' and 'infer' to illustrate their difference". Or some such. Young VE was baffled, because he didn't know the difference. I did, however, check the dictionary afterwards and learnt that the one means "you suggest that" and that the other (expressing it as Cathy Newman would) means "so what you're saying is".
Pedant's corner: Chambers does support the misuse of "infer".
Oh, 55% was my O-Level score for English Language. The days when they were scored numerically: 45% = pass and 90% = top whack. I did get top whack for Greek and Latin, but there's no way I could convince your godfather Peter Pedant of that.