A woman who plotted an ISIS led terrorist attack in Westfield's shopping centre with her husband has had her sentence reduced for "good behaviour."

Sana Khan, 24, was jailed for 25 years after preparing terrorist acts on the anniversary of the London 7/7 bombings in the busy Hammersmith and Fulham spot with then husband Mohammed Rehman.

But she had her sentence reduce by two years at the Court of Appeal on Thursday (July 7), despite Lord Chief Justice for England and Wales, John Thomas, saying Khan "was determined to fulfil Islamic State's cause for jihad by the carrying out of an act of terrorism within the UK."

The couple's plan was foiled when Khan's husband asked Twitter followers: "Westfield shopping centre or London Underground?" after he tested a bomb in his back garden.

Rehman received a life sentence with a minimum of 27 years after he produced explosives and recorded a "martyrdom video" ahead of a possible suicide bombing in a crowded area of London.

During Khan's sentencing at The Old Baily, Justice Jeremy Baker said he believed Khan had "full knowledge" of her husband's terror plot and took a "full and active part in encouraging and planning [it]."

Delivering the verdict today, Lord Thomas said: "She was determined to fulfil Islamic State's cause for jihad by the carrying out of an act of terrorism within the UK.

"She had provided funds to [Rehman], knowing the purpose for which he was using them."

Explaining the reduction of Khan's sentence, Lord Thomas referred to her "previous law-abiding life", adding: "Taking into account her previous good character and her role in contrast to that of Rehman, the appropriate minimum term should have been 23 years."

An advanced plot to detonate in a confined public space

During the couple's trial the court heard how Rehman used his bedroom as a bomb factory filled with deadly chemicals and explosives recipes, and even took to social media for help picking his targets.

Meanwhile his wife funded his Jihadi plot, using payday loans to buy 11kg of fertiliser to make into explosives.

Prosecutor Tony Badenoch QC told the court at the pair's sentencing that Rehman and Khan were behind "an advanced plot to manufacture and detonate a substantial explosive device in a crowded and confined public space".

Courts heard how Mohammed Rehman was a "supporter of violent extremist Islamist ideology"

He added: "Mohammed Rehman was an enthusiastic and vocal supporter of violent extremist Islamist ideology who keenly applied himself to making bombs and gathering all the necessary material to do just that.

"He talked freely about martyrdom on the Internet, his preparations were almost complete and his intentions were clear.

"But for the intervention of the counter terrorism officers at the end of May, this plot would have been carried out."

He said the couple, who wed in secret in a traditional Islamic ceremony but have now divorced, idolised 7/7 bomber Shehzad Tanweer and were plotting an attack in July 2015 to mark the 10th anniversary of the atrocity.