Her Majesty drove past the garage in Dudley where mechanic Fred Budd worked. He and his men joked together that if the Royal car broke down - they would be on hand to help repair it.
Fred never imagined he would be asked to do just that later on in the day.
When the request first came in, he was convinced it was a wind-up - but he was assured by the manager that his services were truly needed, and fast.
So he and his men jumped in a van with some tools, and headed out to repair the Rolls-Royce Phantom III - which had broken down outside Walsall Town Hall.
Fred and his colleagues got to work and eventually the engine was back up and running, much to the delight of the crowd who cheered them on.
"In the back of my mind I was thinking, I hope I get this right with all these people here - but it was relatively simple," he said.
The car was driven to the garage in Sedgley where they carried out the rest of the repairs. and it was back on the road the following day.
The garage received a letter from Buckingham Palace thanking them for their assistance which "resulted in the tour going along without delay".
Fred still has the letter to this day.