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The 'Teenage Dream' singer enjoyed a night out at the theatre with husband Russell Brand's mother in London last night (17th October).
Katy proved she knows how to keep her mother-in-law happy by taking Barbara Brand to watch Ghost: The Musical.
The singer showed off her new pink hair as the pair posed for pictures outside the Piccadilly Theatre.
Katy is currently on the latest UK leg of her California Dreams tour.
Earlier this week, she revealed that she had been enjoying traditional British food during the tour, including baked beans and meat pies.
Katy's tour continues in Liverpool tonight (18th October), before calling at venues across the UK.