It is nearly four years since Katy Perry last released an album and, despite mixed reaction to the three singles which preceded it, she returns to chart prominence in many countries this week with fifth studio album, Witness.

The album is fancied to debut at No.1 in her native USA this weekend and has already made a slew of high debuts elsewhere, opening at No.2 in New Zealand, No.4 in Wallonia, No.5 in Ireland, No.6 in Argentina, Italy and the ...