On Sunday Sir Paul McCartney married his American Jewish fiancée Nancy Shevell in a civil ceremony in London. But the day before, he came to shul with her on Yom Kippur.

Most of the 900 or so worshippers at St John's Wood's Liberal Jewish Synagogue last Saturday were unaware until afterwards of the famous guest who had joined them.

Only a handful of LJS officials had known of the visit in advance after the ex-Beatle's office ordered 15 tickets for Ms Shevell and members of her family, who were over for the wedding.

"We knew her family were coming," said head of LJS security Peter Abrahams, "but we weren't sure if he was coming until an hour before he arrived."

Even emeritus Rabbi David Goldberg had no idea of the celebrity entourage sitting in the balcony when he officiated at the service. "I've got to the stage of eyesight when I am grateful to see beyond the third row, never mind the balcony," he explained.

Some congregants might have cottoned on that something was afoot from a clutch of paparazzi outside the building, who had followed Sir Paul from his home nearby on late Saturday afternoon. But despite their best efforts, the photographers and reporters were unable to slip past the synagogue security.

The family left as quietly as they came after about an hour and a quarter, not staying to break the fast with tea and honeycake at the synagogue. Reports that they had received a blessing from LJS were mistaken.

It is not the first Jewish event that Sir Paul, 67, has attended with Ms Shevell, 51. He made a surprise entrance at a Chabad House (Lubavitch) dinner in New Jersey in December, honouring her father Myron who donated $500,000 for a Torah programme. And it is said to be her influence that led him to play in Tel Aviv last year.

Sir Paul's first wife Linda Eastman, who died in 1998, was Jewish. His second wife, Heather Mills, is not – although she does sell a range of vegetarian products supervised by the Manchester Kashrus Authority.