Ms Horlick is known for her feisty character

Ms Horlick, who is thought to manage about �1bn of SAGM's �6.5bn in funds herself, became famous as the City's 'superwoman' in the late 1990s.

She gained the 'superwoman' nickname for juggling looking after her five children with a high pressure career in the lucrative, male-dominated financial world and prominent charity work.

Ms Horlick could not be reached for comment on Sunday about her career plans.

Not so invincible?

French bank Societe Generale (SG), which part-owns SGAM, will announce her departure on Monday, according to the Sunday Times.

But press reports had differing accounts of what Ms Horlick might do next: the Sunday Times cited people close to her as saying she would have an advisory role within SG before setting up a new venture next year, while the Sunday Telegraph said she had opted for retirement aged 42.

Commentators did agree, however, that SGAM's recent performance has been less sparkling than in the past.

Earlier this year, Ms Horlick's stewardship of SGAM became the focus of a row with another financial high-flyer when Sir Mark Weinberg, chairman of St James's Place Capital, accused SGAM of poor performance. He withdrew �500m in funds from SGAM's care.

Ms Horlick has defended her fund's performance.

Analysts say that SGAM has lost the management of �1bn of pension funds this year, according to the Sunday Times.

Ms Horlick shot to fame in the late 1990s when she lost her job with German fund-manager Deutsche Morgan Grenfell.

She ran a feisty campaign to get her job back, boarding a plane to Frankfurt accompanied by journalists.

She later wrote a book titled 'Can you really have it all?', earning the 'superwoman' tag, though she has denied that she deserves it because her wealth enables her to afford plentiful childcare.