Safiyya Amira Shaikh, 36, was arrested in October by counter-terrorism investigators after she asked undercover cops to supply explosives.
Shaikh, from Hayes, Middlesex and originally named Michelle Ramsden, was charged with planning to commit acts of terrorism after she had surveyed both the iconic cathedral and a London hotel while planning a suicide bombing, according to investigators.
A pair of undercover officers posing as a husband and wife team of extremists had been in contact with Shaikh, who gave one of them bags that she wanted filled with explosives for carrying out an attack, the BBC reports.
Police also say Shaikh had prepared the words of a pledge of allegiance to the terrorist group, according to the Evening Standard, and shared terrorist documents with groups on Telegram.
Appearing at the Old Bailey on Thursday, Shaikh admitted to preparing an act of terrorism, and is due to be sentenced in May.
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