The Finchley fiancée of one of the failed London suicide bombers has lost her appeal against a three-year sentence for helping him escape by dressing him in a burka.

Fardosa Abdullahi, who was 17 at the time of the offence, gave bomb ringleader Yassin Omar her mother’s long black robe to help him flee London the day after the attacks on July 21, 2005.

Abdullahi, 20, who had admitted a charge of assisting an offender, applied for permission last month to challenge her sentence at a hearing before three judges at the Court of Appeal in London.

But the judges rejected her appeal last Friday, ruling the sentence of three years in a young offenders’ institution was not “manifestly excessive or wrong in principle”.

Lord Justice Latham said the case “could have justified a sentence of up to seven years”.

He added: “But there was powerful personal mitigation.

“She was a young girl who was clearly under great pressure from Omar, who had a powerful personality, and others.”

The judges also dismissed conviction challenges by Siraj Ali, 24, from Enfield; Muhedin Ali, 30, from Ladbroke Grove, and Ismail Abdurahman, 26, from Lambeth, who had been convicted of charges of failing to disclose information about terrorism and assisting an offender.

But the three all won reductions in their sentences: Siraj Ali had his 12-year jail sentence reduced to nine years, Abdurahman’s term was reduced from ten to eight years, and Muhedin Ali’s from seven years to four years and nine months.

Sentence appeals by Wahbi Mohammed, 26, and Abdul Sherif, 31, both from Stockwell, were also upheld.

Both had been convicted of charges of failing to disclose information about terrorism and assisting an offender.

Omar was arrested by armed police in Birmingham and was later jailed for life at Woolwich Crown Court, to serve a minimum of 40 years.