They could not sit on an offer for that long. They'd have a week...

They could not sit on an offer for that long. They'd have a week at most before needing to announce any approach or non-binding offers received, which is enough to call an extraordinary board meeting and get their legal team to review the offer. And you don't send your new CFO on her way when an offer lobs in, they are meant to then make the sale happen.

The indicators from other sources (Justin's LinkedIn) show this was underway in early June. I had heard a second-hand rumour from an analyst I know that Helen would be leaving, but I had written that off since it had not been announced. Today is 8 weeks since she started, so likely a mix of hold off as long as they can to announce it, and also insulate the SP from a drop so people can sell their offer shares at a decent profit.