Tom Walker shares cheeky greeting he had for Kate Middleton when they performed together

Tom Walker has revealed the cheeky way he first greeted Princess of Wales when the two performed together at Westminster carol service in 2021.

Speaking on ITV Good Morning Britain , the singer, 31, reflected on his and the Duchess' poignant performance of his song For Those Who Can't Be Here for ITV 's Royal Carols: Together At Christmas, three years ago.

Tom and Kate, 42, played a moving rendition of the poignant song by candlelight at Westminster Abbey in 2021, just before the UK was plunged into lockdown gain.

Speaking to presenter's, Kate Garraway and Richard Madeley , Tom was asked whether who referred to the princess as 'Kate or Catherine'.

The cheeky Scotsman responded joking: 'I can't recall if I'm honest, it was probably "Alright mate"?

Tom - dressed in his usual attire with a beanie cap - described the touching performance as 'amazing' but not something he 'really expected to do' during his career.

The singer was first approached to play for the carol service in October 2021, after Kate heard him perform at the charity event.

Kate then came up with the idea of accompanying him on the piano after music brought 'great comfort' to her during the lockdowns.

Speaking on Good Morning Britain today, he said: 'It was kind of a big top secret, I found out like a month before it happened and then we did a top secret rehearsal.

'I couldn't even tell me parents until really close to the time, just it case it didn't happen and all the rest of it.

'You should have seen my Gran's face when she saw it on telly, she couldn't believe it.'

Tom said the pair had to sit on opposite sides of the room to practice the emotional performance due to Covid.

He previously told MailOnline the whole plan was 'very, very secret', adding that they were both scared of messing it up.

While Kate has played the piano since childhood, the type she was practicing on, which would be the same one used in the performance, was different to hers at home, so she had to get used to it, revealed Tom.

He said: 'We rehearsed the song like nine times and by the end of it she'd absolutely nailed it, and then she went away for a couple of days and practiced it, and then we finally got to do the recording of it.'

He added: 'I think we were both really nervous that it wasn't going to go quite to plan and one of us would let down the other person or whatever, but she was absolutely fabulous – she smashed it.'

The song was written by Tom for 'anyone raising a glass around the table remembering those who can't be with us' this festive season – as hundreds of thousands of people are set to spend Christmas Day in self-isolation with COVID-19, while others think of members of their family and friends they have lost to the virus or other causes.

Tom previously described the Duchess as a 'lovely, kind and warm hearted person' and praised her for having 'absolutely smashed' the performance, adding that it was a 'crazy pinch yourself kind of day' for him.

He also praised Kate for being an 'amazing musician' and said that although she was quite nervous when they first rehearsed in a studio, she went away and 'invested a lot of time and energy into getting it right'.

Tom gave the Duchess a backing track to practise with before the performance and said he was 'shocked at how much better she was' when it came to the actual show, which left him 'really impressed.'

Explaining that his mother had a 'total freak out', he said: 'It was truly an honour playing alongside The Duchess for Royal Carols: Together At Christmas. Without doubt, it was a once in a lifetime experience.

'I thought she absolutely smashed the performance; it's not easy to just jump behind a piano with a bunch of musicians you've never played with before and record live takes to camera, but she completely nailed it.

'She's such a lovely, kind and warm hearted person and she took the time to thank everyone personally for the opportunity to play together.

Speaking to the Mirror in 2023, Tom spoke of his magical performance with the princess. He said: 'I think that was her one and only gig and possibly song, I'm not sure she's planning on making a career of it.'

Though the singer confessed he sound the experience 'daunting', the princess was nothing short of 'lovely' to him.

Tom described the Duchess as a 'lovely, kind and warm hearted person' and praised her for having 'absolutely smashed' the performance, adding that it was a 'crazy pinch yourself kind of day' for him.

The singer's new album I Am is released today, over five years after he came out with his first album, What a Time to Be Alive.

'It's a massive day,' the singer said. 'It's been five years in the making but you know, you can't rush perfection,' he jested.