The classical singer was polished to perfection at the charity do, which raised money for Macmillan Cancer Support.
Katherine channelled Parisian chic in a black polo neck, adding instant zing with an animal print skirt, £35.99 from Zara. And seeing as she's just returned from a safari trip in South Africa, her choice of attire seems quite fitting!
She accessorised with a leather clutch bag, berry red talons and elegant patent courts.
And we're loving her long blonde bob too - sophisticated yet simple, and super-easy to style. Just run your straighteners through your locks, curving inwards as you get to the tips.
It's a low-maintenance style we can totally get on board with!
What do you think of Katherine's outfit? Let us know by commenting below as the best comment across the site each week wins £50!