The 39-year-old singer was heading to the Henry Van Straubenzee Memorial charity carol service at St Luke's Church in London in December last year when she stepped in to help an elderly woman who was being robbed.

She told the Sunday Telegraph newspaper's Stella magazine: "She was clearly in distress, screaming for help.

"So many people just walked past. It was an instinct to rush over and in doing so I got attacked as well.

"I didn't consider that people might know who I am; I gave the police my married name... If it happened again I'd do it again."

In January, a 15-year-old girl - who cannot be named for legal reasons - pleaded guilty to robbery and assaulting a police officer, and said in court she was willing to say sorry for stealing Katherine's phone.

Speaking during her hearing at Highbury Magistrates' Court, she said: "I could apologise. I know that's not going to make up for what I did."

Katherine's phone was later recovered, but the screen had been cracked, and prosecutors say there had been a "clumsy attempt to remove the sim card".

The teenager was handed a six month referral order, meaning she will have to attend sessions with the youth offending team to address her behaviour, and her mother was also ordered to pay £20 compensation.

Katherine has now insisted she would accept the apology.

She added: "It's part of my faith to give people a chance and show forgiveness."

Despite the shock of the mugging, she still attended the carol service because she "didn't want to let them down" - and it only sunk in what she'd done afterwards.

She admitted: "I was shaken up initially. But my instinct is always to keep going, so I got out there.

"Then when I stood there I thought, 'I can't believe I'm actually [doing this].' It was a charity and I didn't want to let them down."