Muslim convert Safiyya Shaikh went on a reconnaissance trip to scope out the London landmark and a hotel. The year-old, born Michelle Ramsden, was arrested after asking an undercover police officer to supply bombs.
At the Old Bailey, Shaikh, of west London, admitted preparing an act of terrorism and will be sentenced in May. She was considered such a threat that MI5 made her the highest-level priority for investigation hcat the weeks before her arrest, according to Whitehall security sources.
It meant she was subject to a level of surveillance reserved for only the most dangerous potential attackers. Over the two months before her arrest in OctoberShaikh built up a relationship with two undercover officers who were posing as a husband and wife extremist team.
lookihg She messaged one of them via an encrypted social media app. But I want to make threats real. I really would love to destroy that place and the kaffir there.
First, there was mounting intelligence of her extremist ideology. Loooing stopped going to a mosque because she suspected she would be reported for her views.
Second, a cyber operation revealed she headed a ificant pro-IS social media chat platform that was pumping out propaganda and urging attacks on targets in Europe. Dutch counter-terrorism investigators linked that to numerous threats in The Netherlands, one of which had led to the evacuation of a church.
Two undercover operations swung into action. In the first, she was befriended by an "online role player" - an officer posing as a fellow extremist to gain more insight into her intentions.
These operations have become increasingly important in fighting terrorism as officers track extremists in social media and work out which ones will convert their talk into attacks. Once Shaikh's intentions were confirmed, a real-world undercover operation had to prove how lookinb she was in the meeting where she explicitly asked for bombs.
Just over a week later Shaikh, of Hayes, visited St Paul's and sent videos to her contact, writing: "I will to the bomb under the dome. She began to court the extremist violent ideology of IS and other jihadist groups and by Shaikh stopped attending mosques.
She was also reported to the government's Prevent programme.