If we assume that all the 3m sells are by the same person, and we also assume that they had less than 3%, then there are a maximum of 3 more trades to come before they are finished. Of course that means that they were playing by the reporting rules, as we haven't seen any TR1's. We'll soon find out.
I assume that idandy is referring to the ex-Hansource shares. Wres RNS'd that they believed that they had passed into Crown ownership. Either the Crown still owns them or they've sold some or all of them.
I believe Degiro is one broker who will lend your shares out for shorting unless you specifically opt out. Have a look through your terms and conditions.
thechaser - we'll only get a TR1 from a buyer if the 3m sells are going to the same entity. This seems unlikely as it appears that the sells are being absorbed into the general market.
If it's not Hansource, then there's an outside chance it could be BlackRock forward selling some of their 5%.