Britain’s youngest female terror plotter, who was arrested after a dramatic raid on a property in Willesden last year, has been found guilty of plotting to carry out terror attacks in London.

Brent & Kilburn Times: Top: Safaa Boular and Rizlaine Boular; Bottom: Mina Dich and Khawla BarghouthiTop: Safaa Boular and Rizlaine Boular; Bottom: Mina Dich and Khawla Barghouthi (Image: Archant)

After a trial at the Old Bailey, Safaa Boular, 18, of south-west London was found guilty of two counts of the preparation of terrorist acts.

Her conviction means she’s Britain’s youngest female terror plotter, as part of the first all-woman Islamic State cell.

Her mother, 44-year-old Mina Dich, and 22-year-old sister Rizlaine Boular had already pleaded guilty to preparing terror acts.

Safaa was spurred into plotting the attack, alongside her mother and sister, after the IS fighter she married online was killed by a drone strike.

The Old Bailey heard they had previously talked of donning his-and-hers suicide belts to achieve martyrdom together.

The 18-year-old secretly discussed the murderous scheme with her sister and mother using coded language that had an Alice in Wonderland tea party theme.

Instead of cucumber sandwiches and cakes, her sister bought a large knife to bring carnage to Westminster in April last year.

Boular first began planning a grenade and gun attack on the British Museum when she was thwarted from joining her IS husband in Syria.

She passed the baton to her sibling after she was arrested and remanded in custody for trying to travel to the war zone.

Boular made no reaction in the dock as she was found guilty on Monday by a jury after two days of deliberations.

Judge Mark Dennis QC put off sentencing for about six weeks for a report to be compiled.

The women were arrested after a dramatic raid on a house in Harlesden Road last year, after counter-terrorism surveillance. Rizlane was shot after police swarmed on the house on the evening of April 27.

At the time, mother of three Rosin Carty described “four deafening shots” as she told her children to move away from the window.

Eyewitnesses said that mourners leaving a funeral at the Mary Magdalen Catholic Church, in Peter Avenue, were turned back during the operation.

A fourth woman was arrested as part of the raid, Khawla Barghouthi. The 21-year-old previously pleaded guilty to knowing details about the plans but failing to pass them on to police.

Dean Haydon, senior national coordinator for counter terrorism, said: “This involved a family with murderous intent, the first all-female terrorist plot in the UK connected to Daesh.

“It’s difficult to say if we will see more females. We have seen young children involved in martyrdom attacks. We have seen Daesh using young children.

“Here in the UK, we have seen an increase in young people, teenagers, getting involved.

“Arrests of youngsters have increased over the last 12 months and clearly that is a concern for us.”

Additional reporting by Press Association