The company, which began trading under the name Exeter Building Contractors Ltd, was formed in 1939 to undertake government contracts being issued at the start of the Second World War.

[6][7] The early 2000s were a time of considerable growth for the business, which involved a series of office openings and acquisitions, such as the Glasgow-based Retail Maintenance Services, Scottish firm John Dickie Construction, and the southern-focused Llewellyn Group.

[2] During late 2003, Rok issued a £116 million bid to acquire rival construction company Galliford Try; however, it was rejected by the board of the latter firm.

[13] The company was negatively impacted by the Great Recession, compelling it to reduce its new-build activities during mid 2009 as its recorded turnover fell by roughly third across the first half of the year.

[14] During the following year, Rok issued a profit warning and suspended its head of finance after having identified allegedly serious failings in the firm's financial controls.