It would seem like a cluster of fornicating misunderstandings. I was there in the Britannia.
1) The complaint about the HF ship was only that switching to his trader while his HF ship was still in Cambridge would put an openly hostile ship in our system as soon as he logged into it again. He left the system, switched to his trader, and was not in any way interacted with when he entered Cambridge. You, in fact, were still there when this happened. Easy thing to miss, but I believe he understood the reasoning.
2) I, personally, fired upon the cricket before you were asked to leave the system, and had no problems dropping his shield. hitboxes are not exactly correct on all ships. many times I have watched my shots pass right through a section of hull without damaging the ship. I hit the model, but not the hitbox. My guess is a combination of dodging and a lack of luck caused your fire to be ineffectual.
Edit: 10 bonus points for sticking up for another player when you felt they were being treated in an unfair manner. 9 points deducted for temper induced accusations of cheating. 9 bonus points because I could have done the same thing. Don't feel the need to be anonymous, anyone who singled you out for some form of retribution would find a price on their heads with a remarkable quickness. Also, it would be quite proper to apologize to the offended party.