Writing in his Live magazine column, the Life Stories presenter recalled how he spotted Timberlake at a bar last month.
He said: "Had dinner with the former Office star Lucy 'Dawn' Davis and her husband, Welsh actor Owain Yeoman, at Soho House tonight, and standing two feet from our table at the bar all night was Justin Timberlake and his new lady Jessica Biel.
"He's always claimed to be my height, 6ft 1in. So imagine my surprise when I stood next to him briefly for a few minutes and his head appeared to reconcile itself with my chin. And that's with a hat on, and what looked suspiciously like built-up heels."