Kate Middleton and Prince William sent a sweet letter to a schoolgirl who went out of her way to send Prince George an invitation to her birthday party.

According to Hello Magazine, the mother of the little girl revealed that they received a heartfelt response from Kensington Palace.

While Prince George’s parents were ‘immensely touched’ by the invitation, they had to politely decline.

A photo of the letter went viral on Twitter, it read:

“The Duke and Duchess of Cambridge have asked me to thank you for your letter, in which you invite Prince George to your 6th Birthday party. I am sorry that it took so long to reply.

“Their Royal Highnesses were extremely grateful for your kind invitation. Having given careful consideration to the possibilities, however, I very much regret that Their Royal Highnesses reluctantly feel they have to decline. Nevertheless, I hope that you enjoyed your birthday.

“The Duke and Duchess of Cambridge were immensely touched that you should take the trouble to write as you did to their son, Prince George. It really was most thoughtful of you and Their Royal Highnesses have asked me to send you their warmest thanks and best wishes.”