RE: The last week.23 Apr 2021 21:27
It's this UT effect. There were two PMEs during closing auction, as RNSd, and an eventual UT of 6p at 16.45, so that is the price that Halifax uses as the closing price. LSE seems to have a different logic to display closing price above. As I understand it , the closing auction UT is the closing price by definition, because that is the purpose of the closing auction, unless someone with direct market access puts in an after hours trade, after the auction.
It's all too messy, and beyond mortal comprehension, just to comply with "rools"