It is one of the first specialist contractors to raise questions about the stability of the market as the race to get schemes open hots up amid slowing London residential sales.

Paul Salmon, managing director of Byrne Bros, said: “We have been concerned recently by the growth of the residential sector in London and consider it prudent to limit our exposure to this particular sector.

“We continually monitor the sectors within which we work and are satisfied with the current balance of between residential projects, commercial projects and infrastructure.”

He said all sectors had expanded this year and Byrne Bros was forecasting turnover to rise from £146m in the year to May 2015 to around £170m in this coming year.

He said: “A symptom of the expanding market in which we now find ourselves is the competition to secure and maintain sufficient resources to carry out our business.

“This is particularly acute at present with labour. We have seen significant wage and salary increases for both operatives and staff over the past 12 months, and the temptation is for people to move employment.”

He added in the latest company report that Byrne had seen this coming early and invested in human resources to ensure labour has always been available and not compromised operation effectiveness.