WIth a bit of research, I dug up the relevant regulation which is civil procdure rule 32.14:
32.14 Proceedings for contempt of court may be brought against a person who makes or causes to be made a false statement in a document, prepared in anticipation of or during proceedings and verified by a statement of truth, without an honest belief in its truth.
She was held in contempt for a "false statement in a document prepared in anticipation of ... proceedings". Perjury per the Perjury Act 1911 is the criminal offense of a witness giving a false statement under oath. Which applies in a given case depends I suppose on whether the false statement is made in a document verified by a statement of truth, or under oath to tell the truth the whole truth etc, and who's making it. It's an interesting distinction. In Upton's case, he was under oath giving oral evidence, so that would be perjury if it applied - but he's a defendant and not a witness, so I don't think the act applies.
Either way - if you're defending yourself in court against a claim, you don't get punished for saying things to defend yourself. I wasn't there - I didn't do it - I really am a woman - the earth really is flat. It's all good.