The Queen's measurements for her Madame Tussauds waxwork jumper were "top secret".
The Queen
The 90-year-old royal's top size was kept under wraps prior to creating the festive jumper, which has a corgi dog wearing a crown embroidered on the front, for her statue, according to the knitwear designer Amber Hards.
The new waxwork figures of the Royal family adorning Christmas jumpers is in a bid to help Save the Children charity.
The creative mastermind has admitted creating the garment for the monarch's still figure was a "surreal" experience.
She told BBC News: "I had the most surreal conversation with Madame Tussauds.
"They [Madame Tussauds] didn't say it was top secret - but I better not say."
The woollen garment was handmade using lambs wool and gold lurex, which took 20 hours for Amber to complete.
And Amber has revealed prior to designing the piece she scoured through the internet in search of the Queen's precise waistline and bust size, but couldn't find a single measurement.
She explained: "Before I got the measurements of the wax work sent to me - I tried to find out what size the Queen was on Google but it didn't say.
"But the jumper is nice and breathable, which is always important for a waxwork."
Not only was Amber told to keep the Queen's dress size secret, she was also advised to come up with something "more tasteful" than most festive knitwear pieces, and not to embed "shoddy lights" to the garment.
She said: "They wanted a corgi with a crown but nothing tacky and no shoddy lights - it had got to be more tasteful."
The royal waxworks can now be seen in the popular London attraction throughout this month.