Fans were able to see the pop legend while the traffic lights remained on red.
“Nobody really got chance to speak with him,” said Morton.
The tour guide revealed it was not his first encounter with the star, having come across him when he used to work at the Cavern Club.
“We were told not to take photos but I managed to sneak one,” he said.
Sir Paul, who famously first found fame in his home city with The Beatles before they became global superstars, was in the city to present actor Stephen Graham with an award in a ceremony at his performing arts school.
Graham, who grew up in the Merseyside town of Kirkby, will be presented with a companionship of the Liverpool Institute for Performing Arts (LIPA) by the former Beatle and co-founder of the school.
LIPA has other Beatles connections, as it is based at the former Liverpool Institute school attended by Sir Paul and George Harrison and is neighbour to Liverpool Art College, where John Lennon studied.
