His departure comes in the wake of controversy surrounding his previous role as head of the Covid co-ordination directorate of the Scottish Government, where he advised officials to delete WhatsApp messages during the pandemic.

ICAS confirmed Mr Thomson’s resignation, citing “personal reasons,” and highlighted that it was effective from 31 January. As the head of the regulation board, Mr Thomson was responsible for overseeing policy, investigating complaints, and monitoring professional standards within the accounting profession.

Mr Thomson, a civil servant since 1988, had a history of serving various roles in the Scottish Office and government, including being the director-general for strategy and external affairs. He was appointed as chair to ICAS, from 1 January 2024, following the departure of Philip Rycroft who stood down as chair in October 2023.

The controversy surrounding Mr Thomson arose during the UK Covid inquiry’s evidence sessions in Edinburgh. It was revealed that Mr Thomson had advised officials, including key figures like Jason Leitch and Lesley Steedman, to delete their messages due to the possibility of them being made public through freedom of information requests, The Times reports.

While defending his comments during the inquiry, Mr Thomson denied any culture among senior officials to delete messages related to the Covid-19 pandemic. However, subsequent revelations indicated that top officials, including Nicola Sturgeon and John Swinney, had indeed deleted their messages.

Yesterday, Ms Sturgeon said: “Ken Thomson is somebody I’ve worked with throughout my time in the Scottish Government and he is a civil servant, as I say, of the utmost integrity and the utmost professionalism.”

ICAS announced it will shortly begin the process of appointing a new chair of the regulation board.