Cameron Ross, 24, from Edinburgh, was going to celebrate mum Lynda’s birthday when he found out the A list actor was just yards away, in the capital’s George Street.
He dashed in to a nearby card shop and waited for Clooney to emerge from the People’s Postcode Lottery offices.
The actor picked Cameron out in the huge crowd and happily signed the card, wishing his mum a happy birthday.
Hotel manager Cameron said: “It’s my mum’s 60th birthday and she’s having lunch in Harvey Nicks.
“She thinks I’m working but I was going to go up and surprise her with some flowers and her birthday card.
“A lady stopped me and said ‘do you know George Clooney’s in there?’
“Mum’s a big fan of George Clooney -- so I just ran back in to Paperchase to buy another birthday card.
“I waited for half an hour but he couldn’t have been nicer. He came over to me and shook my hand.
“I said ‘it’s nice to meet you, will you sign a birthday card for my mum?’.
“He was happy to sign it.
“Above his signature I’m going to write, ‘to Lynda, happy birthday, love...
“My mum’s got multiple sclerosis so her 60th is quite a big birthday for us. My sister is flying up from London to celebrate.
“She’ll be ecstatic to get a card from George Clooney”.