Dave Lewis has a huge job on his hands - not only is he taking the helm at the UK’s biggest retailer, he is inheriting a business struggling to turn itself around in the face of the most challenging conditions grocers have faced for 40 years.

Tesco's new boss Dave Lewis

But Lewis’ experience at Unilever, where he heads the most profitable multi-category personal care business in the world, working with many brands sold in Tesco stores, should stand him in good stead.

Unilever Personal Care has annual sales of around €20bn at 2013 exchange rates. Its portfolio includes five billion-euro brands including well-known names such as Dove soap, Vaseline and TRESemme haircare.

When he moves to Tesco in October it is hoped that his business nous and market knowledge will steer Tesco on the right path, after it posted its worst quarter in 40 years under departing boss Philip Clarke’s leadership and today warned on profits.

It is a big change for Lewis though. A Unilever lifer, he has been with the FMCG giant for 27 years, latterly serving as president of the personal care business and as chairman of the UK and Ireland. Lewis joined Unilever straight from Trent Polytechnic in 1987 where he started as a trainee at Lever Brothers.

Lewis worked his way across the whole breadth of the global business and in 1996 he moved to South America to be marketing director of the River Plate business, which serves Argentina, Uruguay and Paraguay.

He then moved to Indonesia in 1999 to become managing director of Unilever Indonesia’s personal care business and regional innovation leader for personal care South East Asia. In his tenure there he battled political unrest and hyperinflation to grow the business at 30% a year.

It wasn’t until 2005 that he returned to the UK and took up the role of managing director of home and personal care. He was then appointed chairman of Unilever UK and Ireland as the company consolidated its food, home, personal care and ice cream into a single business.

In 2008, when he was 42, his public profile was boosted when he chaired a Government working group on how businesses and government could tackle public health issues such as obesity together.

Tesco chairman Sir Richard Broadbent says Lewis will bring a “fresh perspective” and he that he is very experienced at turnarounds both in the UK and overseas. Broadbent says Lewis also knows the Tesco business well.

But despite Lewis’ experience on the product and brand identity side, his lack of retail experience is a concern for some observers.

Bernstein senior analyst Bruno Monteyne says: “Clearly the talent is there, but will the lack of retail experience be a problem to set a new strategy for a retailer that is having an existential crisis?”

One source told Retail Week that moving from FMCG to retail has a “very high rate of rejection”. The source said while there are some well-regarded retailers who have started out in FMCG, there are many more that haven’t made it and that to go straight in at the top to the “blood and guts of UK grocery retail” will be a struggle.

But independent analyst Nick Bubb says: “Dave Lewis knows nothing about retailing, but maybe that doesn’t matter because as a leading supplier he certainly knows how to win price wars and perhaps that is the big issue now facing Tesco in the UK.”

The source added that Lewis is a marketeer so “clearly that’s where they [Tesco] think their problems are”, and that he is “measured and balanced”.

Lewis, a keen runner - once completing the London Marathon in four hours and 18 minutes- will need to be measured and balanced when he takes over. But he will also need to keep running to turn around the Tesco juggernaut.