The 23-year-old singer said she was "terrified" after the friend was abducted at gunpoint and held hostage for a week.

The friend and another man, both in their 20s, were working at a sports store in west London last month when a group of armed men allegedly entered the store and bundled the shop workers into a car.

The group are accused of holding the pair hostage at an address in Thamesmead, south east London, and demanding a ransom of £75,000 from their families.

Lily's friend and his co-worker were found by police a week later on August 9. They were handcuffed with their heads covered but were unhurt.

Allen wrote on her blog: "Thank you to the Met for getting my friend back, we were all terrified and from what I hear you guys did an amazing job."

On Tuesday night she co-hosted the GQ Men of the Year Awards with Sir Elton John in Covent Garden, London, where she turned heads wearing a stunning metallic Dolce and Gabbana dress.