"Midnights" becomes Swift's longest-ruling LP in the U.K.
"Harry's House" shifted north of 460,000 U.K. chart units across the year.
They are the first girl group to win in the category and the first group of any type to win since Florence + the Machine in 2009.
Becky Hill was named artist of the year at the event, which was held in London on Thursday night.
Walliams is one of the U.K.'s best-known TV personalities & a successful children's author.
