Ann: Target's Statement, page-113

On-market takeover.
"The bidder will typically set an offer period of one month, but is it common for several extensions to the offer period to be made by the bidder during the course of the market bid to allow target security holders more time to accept. The maximum offer period, including extensions, is 12 months.
The bidder may increase its offer price at any time before the last five trading days of the offer period. If the bidder does so, unlike for an off-market bid, the bidder does not need to pay the increased consideration to target securityholders who accepted the market bid before the price increase. That can make an on-market bid cheaper for the bidder than an off-market bid."

MCR holders may get cold calls for a further 12 months.

Not sure if extensions can be made within the last five days.