Downer will pay £24m in cash for the stake when the deal completes in early 2019.

KHSA, which was acquired as part of the Mouchel group of companies in 2015 reported £7m profit last year and has total assets of £52m.

Proceeds from the sale will be used to accelerate the reduction of Kier’s net debt.

Kier is aiming to raise up to £50m from non-core business disposals as part of a plan to cut its debt mountain of £375m.

Two months ago Kier has sold its third-party pension management business for £3.5m.

Alongside £20m annual savings from its Future Proofing Kier streamlining programme, the group aims to reduce debt to £250m and be in a net cash position by 2021.