The independent contractor jumped from third to first after lifting turnover 18% to £707m, knocking last year’s leader TClarke down to third.

EDF-owned Dalkia held second place with turnover up 8% to £656m, just £1m ahead of TClarke on £655m.

Wates-owned SES completed the breakaway pack after revenue surged 27% to £590m.

The gang of four are now operating in a league of their own, with a near £200m gap back to fifth-placed Dornan Engineering.

But Dornan proved the big mover in this year’s rankings.

Turnover leapt 77% from £222m to £392m, catapulting the contractor from 11th to fifth.

Private equity-owned Phoenix ME also kept up its rapid rise, climbing one place to sixth after growing turnover 24% to £378m.

The latest Building Engineering Services Association Top 30 UK M&E Contractors report puts combined turnover among the ranked firms at £6.8bn against £6.2bn previously.

BESA said the wider sector had shown strong resilience after collective turnover among leading firms recovered from £4.7bn following the pandemic to more than £6bn.

Data centres and wider digital infrastructure are leading the charge, alongside healthcare, defence, energy transition and work driven by the Building Safety Act.

Office construction and fit-out are also maintaining a steady workload, while the looming handback of PFI healthcare assets is expected to create a major refurbishment and retrofit market.

Gokhan Hassan, managing director of GHCS and GH Engage, which carried out the financial research, said: “Since recovering from Covid in 2022/23 the collective turnover figure has risen from £4.7bn to more than £6bn which coincides with the explosion of the mission critical sector.”

BESA warned that fixed-price contracts, project delays and inflation were still squeezing margins and cash flow.

Contractors are responding by becoming more selective, targeting longer-term markets and clients willing to bring M&E specialists into projects earlier.

BESA chief executive officer David Frise said: “This is an exciting time for our industry.

There is great demand out there for high-quality building engineering work and the challenge of turning opportunity into business success is also driving companies to be more innovative.”

The new ranking also includes several fresh entrants, including Bancroft at 20, MCS at 21 and Price Building Services at 24.