LONDON - Not far below the pomp and pageantry is a rollout of a remarkable security operation.

It’s one that includes average Brits who are being mobilized to serve Queen and country.

On Wednesday, outside Westminster Abbey, the official protection detail boiled to the surface as members of a Metropolitan Police unit crawled out of the ancient sewage system after checking the underground.

Nearby, sniffer dogs worked and surveillance choppers marked time above Big Ben until the wedding party would later pull in to rehearse their own important steps.

An estimated 5,000 police officers, as well as soldiers, will protect the valuable couple and their VIP guests.

But the net is being flung wider than that.

This city has a history of civic pride — as well as civil disobedience — so police have issued a call to everyone.

“With thousands of people (arriving for Friday’s wedding) we need you to be our eyes and ears,” said London police Commander Christine Jones.

Officials hope ordinary citizens will be on guard for the royals.

Police have told QMI Agency they’ve seen an increase in "chatter" among protest groups, but they have so far found no direct threat to the wedding.

London is always under a severe threat level and there’s no lack of organizations — from anarchists, to the hardline Muslims Against Crusades, to the far right English Defence League to dissident Irish republicans — that would like to steal attention away from Prince William and his bride, Kate Middleton.

Several groups now say they won’t protest. But security forces are braced for — they say — any scenario.

Jones would only say their response to a crisis would be “robust, decisive and flexible,” but stressed they are manning a celebration and not a protest.

That makes people like Sheree Zielke of Edmonton very happy.

While she and her husband have a hotel room here, Zielke — an author — felt the need to stay on the street, near where the police came out of the sewer.

A sign behind her read: “Hi. Yes, I am a crazy Canadian. I have no tent.”

“A romance novelist needs to be at the wedding of the century,” she reasoned, as it was left up to husband, David Thiel, to fetch a quilt from their hotel.

Added the grandmother: “I’m right out front of Westminster Abbey, and I can’t imagine something bad happening here.”