Ann: Proposed Cancellation of London Listing, page-4

Yes to both questions.
Retail investors will not like the fact that they are no longer listed locally so they will want to exit before Friday 24th (actually 8 am so the day before).
WRT administrative efficiencies, I guess it means they don't have to pick times when both exchanges are closed to release announcements and maybe the rules are slightly different so there is a compliance cost as well. I don't expect a funding announcement prior to 24/09.