Ann: Enforcement proceedings in respect of TER's unsolicited bid, page-11

They are using your articles of association to block TER, and not the city code. It looks good on paper but now the courts will decide if its fair and reasonable and whether your articles of association have the legal standing. The English courts will rule by common law so if you want to guess how good the case is goggle some common law decisions of a similar nature. The judges must follow precedence in English courts.
Of course TER may just change the offer or retract it. Hopefully they do this before they use up all your cash in the courts.
Dragging this out in court will serve none any favours.