Here are five facts about the new chief executive:

- Roberts, 48, joined Sainsbury's as retail and operations director in July 2017, with oversight of the logistics systems that underpin the performance of its 1,400 stores, 900 Argos outlets and large online business.

He recently expanded his role to take charge of the retail operations of Argos, the general merchandise brand that is being integrated into the larger group after it was bought in 2016.

- Roberts has rebuilt the supermarket's operating model in its stores, investing in new technology that has improved product availability and the group's productivity. He has also revamped the leadership structures of stores and standardized shop floor workers' contracts.

The improved efficiency has enabled the group to invest more in lowering prices for customers, it said.

- Roberts, who lives in York, northern England, was previously the president of the pharmacist and health group Boots UK and the executive vice president of its owner Walgreens Boots Alliance. During his time he invested in the group's online offering and sought to broaden its appeal.

- Roberts started his retail career at the age of 16 and joined the training program of Marks & Spencer two years later. He spent 15 years at the British retailer where he held operational and customer leadership roles across stores, divisions and its central operations.

He is chairman of the Institute of Customer Service.

- In 2011 Roberts was named joint chief operating officer of Boots UK, alongside his colleague Ken Murphy. Irishman Murphy is due to take over the top job at Britain's biggest retailer Tesco later this year, pitting the two men against each other in the most high profile retail jobs in Britain.

(Reporting by Kate Holton; Editing by Susan Fenton)