There were echoes of the recent bold coiffures showcased by Madonna and Vivienne Westwood in the 'do, which was swept straight up and accessorised with a black hair band.
And it perfectly complemented Katherine's chic blue and green sequinned mini which she teamed with towering black heels.
The 29-year-old opted for her striking new look in honour of her role at the Women of the Year Awards.
After a mad dash from the airport – the details of which she tweeted about - the Welsh singer arrived on time to present Dame Vera Lynn with a lifetime achievement award.
It was entirely fitting that the original forces sweetheart should be presented with her trophy by Katherine, whom the 92-year-old Londoner first encouraged to go out and entertain the troops.
In front of an audience that included Gordon Brown's wife Sarah and former TV presenter Fern Britton, Dame Vera received a standing ovation as she accepted her accolade.
"It's lovely to be recognised all those years after the event," said the star, who last month became the oldest living artist to top the UK album chart.
"But I'm still very proud of the fact that We'll Meet Again is a song that has gone around the world… what better words can you have when your loved one has gone to war and you leave your family behind."