The contract, described as “urgent”, is for the development of an “Outline Business Case” for the 2031 census. The decision has drawn censure due to both Deloitte’s record and the significant challenges faced by the previous census in 2022.

The 2022 Scottish census, delayed by a year, suffered from low response rates, forcing ministers to extend the deadline. It ultimately achieved an 89% return rate, falling short of its target and well below the 97% achieved in England and Wales.

Robin Mcalpine of the think tank Common Weal described the 2022 survey as “effectively the first failed census in modern history” and condemned the new contract. He warned of the “privatisation by stealth” of Scotland’s public sector and questioned why a firm fined multiple times, including a £15 million penalty in 2020 for audit failures, was shaping core public data.

“It is beyond belief that Scotland’s emaciated and failing civil service is not capable of designing a census,” Mr Mcalpine said, adding the move should be of “very great concern to every Scottish citizen”.

A National Records of Scotland spokesperson told The Herald said: “NRS will run and is fully responsible for the next census in Scotland in 2031.

“Deloitte were commissioned for a time-limited period to assist specifically with the development of an Outline Business Case. This was based on the specialist skills and expertise they could provide in this area.

“The 2022 census delivered valuable data for Scotland, with NRS gathering, analysing and presenting over a billion statistics which represented Scotland’s whole population. These statistics are already being used to inform decision making across our economy and society.”

The spokesperson also maintained that the 2022 census delivered valuable data, noting that the UK’s statistics regulator had granted its results an “Accredited Official Statistics” designation for its quality and comprehensiveness.