London Mayor Sadiq Khan was among those who attended Synagogue on Saturday as part of the “Show up for Shabbat” initiative after the Pittsburgh shooting.

A week after 11 people were murdered at their shul, Rabbi Neil Janes implored people at West London synagogue to "focus on amplifying small and yet simple acts so that the voices of hope are louder than those of hate".

The mayor called the service “deeply moving", adding: "London stands shoulder-to-shoulder with the Jewish community here and around the world.”

The Show up for Shabbat initiative was spearheaded by the American Jewish Committee, in response to the murder of 11 Jews who were shot in the Tree of Life synagogue in Pittsburgh during Shabbat morning services on October 27.

It was promoted across social media through the hashtag #ShowUpForShabbat, as well as by Jewish organisations and denominations across the religious spectrum, with thousands of Jews and non-Jews attending Shabbat services together this past weekend.

No Cabinet or Shadow Cabinet ministers are believed to have attended. 

Rabbi Neil Janes said in his sermon: “I cannot tell you how truly sustaining and significant the small act of sitting in pews with us all across the world has become.

“Last week Jews were gunned down in pews like these, today in defiance we sit together with the human family to strive to increase the goodness in the world, to bring light to darkness, to show that we will not be cowed by violence in our observance of our faith or engagement with the world.”

He added: "When the world stands on a precipice with the resurgence of populism, fascistic and far left ideology and conspiracy theories – small acts of kindness will not be enough.

"Friends, we need to be more organised than that if we are going to defeat terror and hate and build a better world."