SHE was the power behind the throne as Gordon Brown achieved his prime ministerial ambitions.

Since leaving Downing Street more than two years ago, Sarah Brown has devoted herself to charity campaigning, raising two young sons, John and Fraser, and writing a book about life at No 10.

Now Mrs Brown, who as Sarah Macaulay co-founded the successful public relations agency Hobsbawm Macaulay Communications when she was 30, has returned to the world of business, joining luxury department store Harrods as a non-executive director.

The famous emporium is no longer owned by the flamboyant Mohamed Al Fayed, but is in the hands of a Qatari-owned business.

Mrs Brown will advise Harrods on developing marketing plans, including corporate social responsibility programmes.

The store said the 50-year-old would draw on her extensive experience across a range of businesses and not-for-profit organisations.

According to documents filed at Companies House, Mrs Brown describes herself as a charity director and writer.

She said: "I look forward to my return to business in joining the Harrods Group board and welcome the opportunity to work on the marketing and corporate social responsibility plans for this world-renowned British brand."

Mrs Brown was born in Buckinghamshire to schoolteacher mother Pauline and Scots-born father Iain, who worked for the Longman publishing company, and spent some of her early childhood in Fife.

She also lived in Tanzania with her parents for a spell but settled with her mother in London at the age of seven following her parents' divorce. After graduating with a psychology degree from Bristol University, Mrs Brown worked at brand consultancy Wolff Olins specialising in Labour events, such as the Manufacturing Matters Conference and party donor events.

She then co-founded the PR firm Hobsbawm Macaulay with schoolfriend Julia Hobsbawm.

She first met her future husband at a Labour Party event her firm was organising, and they married in 2000 in a Church of Scotland ceremony at the then Chancellor's North Queensferry home.

She left work a year later when expecting daughter Jennifer Jane, who died at 10 days old after being born two months prematurely in hospital in Kirkcaldy.

In a series of essays for a charity book, she described how much the tragedy had changed her life.

Mrs Brown wrote: "I had assumed I must find a way to recover and resume my life, which proved impossible. Instead I realised that the loss of Jennifer had changed me forever, and importantly I realised that this was OK."

Qatar Holding acquired the Harrods group for £1.5 billion in 2010.

It is unclear how much Mrs Brown will be paid or how many days she will dedicate to her role.