According to the pop princess, she was mingling with other performers at the exclusive Buckingham Palace Diamond Jubilee reception when Prince William came over to chat.
And it seems he couldn't help sharing Kate Middleton's hen do details as he spoke with Cheryl, revealing his wife had dressed up as her for the occasion, and sung number one hit Fight For This Love.
'Did you know you’ve got a bit of competition?,' he joked to songstress.
After spilling the beans on Kate's Cheryl costume - complete with split leggings and peaked hat - he added that the Duchess had also learned Cheryl's dance routine for the bash, organised by sister Pippa before the royal wedding in 2011.
'She even learned the dance routine and was step perfect by all accounts,' reveals Cheryl.
'I could just imagine her and it was so surreal.'
How we wish we had been a fly on the wall…
WATCH Kate Middleton at the Queen's Diamond Jubilee…
Cheryl - My Story is in stores today.
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