Engineering services — the design consultancies, infrastructure engineers and technical specialists behind Britain’s bridges, grids, plants and data centres — is really three businesses wearing one badge, and they earn three different livings. Among the 208 UK engineering-services companies that publish a full profit-and-loss, booking £15.6bn of combined turnover, the contractors who build what others design keep 1–3p in the pound (Dornan 1.5%, Amey Highways 1.9%); the consultancies who sell engineering hours keep 5–15p (even employee-owned Mott MacDonald, at £2.52bn the largest genuine consultancy in Britain, converts about 5% to pre-tax profit); and the handful of firms that own a product or a scarce specialism keep 23–28p — Boustead International Heaters at 22.9% on fired heaters, and one specialist consultancy, Fichtner, at 27.9% on energy advice. (S.S.S. Gears posts a headline 50.5%, but most of that is gains on a large investment portfolio — its clutch business trades at about 13%.) Figures are approximate — verify against a company’s own accounts before relying on any single number.
Read the names first
Three things change how you read every number below.
The biggest name isn’t a consultancy. Babcock International — £4.83bn of turnover, £329.1M of pre-tax profit, 26,858 staff — is a listed defence and nuclear engineering contractor that happens to sit in this category. It alone accounts for roughly 31% of the map’s turnover, and comparing its economics (long government contracts, dockyards, submarines) with a design consultancy’s is meaningless. We’ve kept it out of every competitive read below.
The big firms file in layers. Mott MacDonald appears twice — the group at £2.52bn and its main UK operating company at £1.04bn, which sits inside the group’s figures. Buro Happold does the same: a group-level entity booking £187.9M and the consulting-engineers company at £54.0M. One firm, two sets of accounts — the tables below use one entity per group and note the other.
Some of the largest entities are internal plumbing, not market participants. Two arms of Renesas, the Japanese chipmaker, sit near the top: a chip-design company at £302.9M, and an operations entity that books £306.0M of chip sales through 21 employees — the group’s sales-and-operations vehicle, not engineering sold on the open market. Net out Babcock, the double-counted entities and the captives and the market-facing engineering-services trade visible here is nearer £9bn.
The giants
The top of the map is mostly other people’s companies: of the ten largest, only Babcock and Mott MacDonald answer to British owners.
| Company | What it is | Turnover | PBT | Turnover YoY |
|---|---|---|---|---|
| Babcock International Group | listed defence & nuclear engineering contractor | £4.83bn | £329.1M | +10% |
| Mott MacDonald Group | employee-owned global engineering consultancy | £2.52bn | £123.3M | +6% |
| Mott MacDonald Ltd | its main UK operating company | £1.04bn | £84.7M | +4% |
| Jacobs U.K. | UK arm of the US-listed consultancy | £763.8M | £111.7M | — |
| Linxon | turnkey electrical-substations venture | £463.4M | £10.7M | +43% |
| Renesas Electronics Operations Services | sales-and-operations vehicle of the Japanese chipmaker | £306.0M | £5.5M | −22% |
| Renesas Design (UK) | the group’s UK chip-design company | £302.9M | £78.4M | −2% |
| Dornan Engineering Services | Irish-founded M&E contractor (data centres) | £222.6M | £3.4M | +183% |
| Frazer-Nash Consultancy | defence & systems consultancy (KBR-owned) | £212.6M | £31.4M | +26% |
| Fugro GB (North) Marine | marine survey arm of the Dutch group | £209.0M | £10.3M | −5% |
Just below the cut: Amey Highways (£196.3M, £3.7M — road-maintenance contracting) and Buro Happold’s group entity (£187.9M). Mott MacDonald Ltd and Buro Happold Consulting Engineers sit inside their groups’ figures, not alongside them. Both Renesas entities report in US dollars; their sterling figures here are converted and approximate.
Read as a consultancy market, the interesting split is at the profitable end. The government- and defence-adjacent consultancies run the best big-firm margins on the map — Frazer-Nash converts 14.8%, growing turnover 26% and headcount 20% in a year on the back of defence and nuclear demand, and Jacobs U.K. shows 14.6% at the pre-tax line, though that includes dividend income from subsidiaries — its operating margin on the hours business is nearer 11%. Mott MacDonald, the standout British firm — employee-owned, 18,778 staff, growing steadily — keeps about 5%, almost exactly the map’s median margin. That is what selling hours looks like even when you’re excellent at it: the wage bill scales with the work, and the client keeps most of the value. The contracting names (Linxon 2.3%, Dornan 1.5%, Amey Highways 1.9%) aren’t badly run — they’re a different business, buying equipment and subcontract labour on the client’s behalf, and their thin margins sit on largely pass-through revenue. Don’t compare them with a consultancy’s.
Where the money is: own the kit, not the hours
The best-run mid-market firms (£5M–£100M, ≥5% margin, captives excluded) split the same way. Well-run fee consultancies cluster at 8–12%; the firms above 20% own something — a product line, a technology, a niche monopoly.
| Company | What it is | Turnover | PBT | Margin |
|---|---|---|---|---|
| Tetra Tech Environmental Management | environment & planning consultancy (US-owned) | £86.6M | £9.9M | 11.4% |
| Comau U.K. | industrial-automation integrator (Italian group) | £71.7M | £8.4M | 11.8% |
| Cowi UK | infrastructure consultancy (Danish group) | £69.0M | £8.3M | 12.1% |
| Boustead International Heaters | process fired-heater design & supply | £55.2M | £12.6M | 22.9% |
| Buro Happold Consulting Engineers | building-engineering consultancy | £54.0M | £4.9M | 9.2% |
| Silverstream Technologies | ship air-lubrication systems | £53.7M | £5.0M | 9.2% |
| Hyde Aero Products | aerostructures manufacturer | £42.7M | £4.3M | 10.1% |
| KBC Process Technology | process-simulation consultancy & software | £41.7M | £2.4M | 5.9% |
| Classic Lifts | lift installation & service | £41.0M | £2.3M | 5.7% |
| Dalcour Maclaren | land & consents consultancy for utilities | £39.0M | £3.1M | 7.8% |
| Fichtner Consulting Engineers | energy consultancy (German group) | £36.8M | £10.3M | 27.9% |
| Parsons Brinckerhoff | infrastructure consultancy (WSP group) | £36.6M | £3.7M | 10.2% |
| S.S.S. Gears | turbine & marine clutch maker | £24.2M | £12.2M | 50.5% |
…and seven more profitable operators between £5M and £33M, from IKM Testing (10.8%) to Hilson Moran (8.5%). S.S.S. Gears’ 50.5% is flattered by a £7.0M fair-value gain on its listed-investment portfolio — the trading margin is nearer 13%; see below.
The pattern is hard to miss — but read the top line with care. S.S.S. Gears, a 45-person maker of self-synchronising clutches for turbines and ships, heads the table at 50.5%, yet £7.0M of its £12.2M pre-tax profit is a fair-value gain on a £69.7M listed-investment portfolio, with another £2M of investment and interest income on top: this is an investment-rich family company whose clutch business trades at about 13% — a good product margin, not a 50p-in-the-pound one. The genuine product story is Boustead International Heaters, earning 22.9% designing and supplying process fired heaters — a project business, but one where the engineering is embedded in equipment rather than billed by the hour. The one consultancy that genuinely breaks the hours ceiling is Fichtner: 27.9% from 182 people advising on energy and waste projects, roughly £56k of pre-tax profit per head — a reminder that deep specialism in a capital-hungry sector can command product-like pricing. Beneath those outliers, the dependable tier — Cowi, Tetra Tech, Parsons Brinckerhoff, Buro Happold, Hilson Moran — shows what good looks like for a firm selling expertise by the hour: 8–12%, year after year.
The shape of the market
Scale pays in this trade. The share of firms making money rises in a straight line with size — 43% profitable under £1M, 71% at £5–25M, 86% at £25–100M, 95% above £100M — because a consultancy’s costs are people, and bigger firms can keep those people utilised across more projects and survive the write-down on any single one. The £5–25M band is the market’s centre of gravity: 96 of the 208 firms.
Growth, read with care
The fastest growth on the map is mostly ramp-up, project timing or someone else’s boom. Fluence Energy UK (+4,504% to £106.5M, 8.6% margin) is a grid-scale battery-storage supplier in its first real year of delivery — a ramp from a standing start, not a trend. Dexory (+477%) is a venture-funded warehouse-robotics developer losing £22.6M on £3.6M of revenue — pre-commercial economics that don’t belong in any margin comparison. Comau’s +311% is project-based automation revenue landing in one year. The clearest genuine demand signal is the data-centre build-out: Irish-founded M&E contractors Dornan (+183% to £222.6M, staff +28%) and Kirby Group (+110% to £85.0M, staff +23%) are growing explosively at 1.2–1.5% margins — enormous revenue, contracting economics, almost nothing kept. The rare firms growing fast and profitably and hiring — Frazer-Nash (+26%, 14.8% margin, staff +20%), K&M Technical Services (+110%, 11.7%, staff +18%) — are what real engineering growth looks like.
| Company | Turnover | PBT | Margin | TO YoY | Staff YoY |
|---|---|---|---|---|---|
| Fluence Energy UK | £106.5M | £9.2M | 8.6% | +4504% | +200% |
| Dexory | £3.6M | −£22.6M | −636% | +477% | +61% |
| Comau U.K. | £71.7M | £8.4M | 11.8% | +311% | +27% |
| Dornan Engineering Services | £222.6M | £3.4M | 1.5% | +183% | +28% |
| Gebhardt Intralogistics UK | £39.8M | £1.1M | 2.9% | +143% | +3% |
| Idex Biometrics UK | £5.3M | £1.6M | 29.8% | +120% | −12% |
| K&M Technical Services | £21.3M | £2.5M | 11.7% | +110% | +18% |
| Kirby Group Engineering (UK) | £85.0M | £1.1M | 1.2% | +110% | +23% |
| Intermarine UK | £55.1M | £2.7M | 4.8% | +98% | +236% |
| Leidos Industrial Engineers | £18.1M | £544k | 3.0% | +96% | +10% |
Idex Biometrics UK is the local arm of a Norwegian biometrics group — its 29.8% margin on intra-group work says nothing about the open market.
Market structure and vintage
On paper this is one of the most concentrated markets we’ve mapped — the top five hold 61.5% of turnover. In practice that number is an artefact: it’s Babcock (31% by itself), Mott MacDonald counted twice, and Jacobs. Set those aside and engineering services is what it has always been — a deep, fragmented mid-market of specialist firms, where the top 100 are needed to reach 96% of turnover.
Ownership tells the same story as the giants table: 119 of the 208 firms are corporate-owned against 80 individual-owned, and about 11% carry a Holdings/Group/Bidco-style name — the structural fingerprint of a buyout or a planned exit. Consolidators have noticed that dependable 8–12% fee businesses are worth rolling up.
The vintage profile is old and steady — 56 firms pre-date 1990 and another 44 are children of the 1990s, the established consultancies that anchor the mid-market. But the 2016–20 cohort (34 firms) is the second-largest, and it’s where the energy transition shows up: battery-storage suppliers, marine clean-tech, robotics — the map’s product owners of the 2030s, if they survive the burn.
What the map shows
- One badge, three businesses. Contracting other people’s builds pays 1–3% on largely pass-through revenue; selling engineering hours pays 5–15%; owning the product or a scarce specialism pays 23–28%. Comparing margins across those models is a category error — the split is the market.
- The hours ceiling is real. Even Mott MacDonald — employee-owned, £2.52bn, the best British consultancy at scale — keeps about 5%, the map’s median. The premium end of hours is defence and nuclear: Frazer-Nash runs near 15%, and Jacobs U.K. about 11% at the operating line.
- The profits belong to the kit owners. Fichtner converts 27.9% on energy advice; Boustead 22.9% on fired heaters. (S.S.S. Gears’ headline 50.5% is mostly investment-portfolio gains sitting on a ~13% trading margin.) Deep specialism prices like a product; general expertise prices like a salary.
- The top of the map flies foreign flags. Of the ten largest entities, only Babcock and Mott MacDonald answer to British owners — the rest are the UK arms of American, Japanese, Swiss-Canadian, Irish and Dutch groups, and two are Renesas group vehicles rather than open-market engineering businesses.
- The data-centre boom is the growth story — for revenue, not profit. Dornan (+183%) and Kirby (+110%) are riding it at 1.2–1.5% margins; the value is accruing to their clients.
- Scale pays in a people business. Profitability rises monotonically with size, from 43% of firms under £1M to 95%+ above £100M.
Methodology and caveats
This covers only the UK engineering-services companies that publish a full profit-and-loss — 208 of a register of around 1,230 — so the long tail of small practices filing abridged accounts is invisible here, and the £15.6bn total is a floor for the sector, not the market. Babcock International is included in the totals but excluded from competitive reads; where a group files through several entities (Mott MacDonald, Buro Happold, Renesas), the analysis uses one entity per group and notes the others. Business-type labels are directional, inferred from what each company publishes about itself. Large single-year growth may be ramp-up, project timing or acquisition rather than organic demand, and thin contracting margins sit on substantially pass-through revenue. Margins are pre-tax profit over turnover; where a headline margin is dominated by investment or one-off gains rather than trading (S.S.S. Gears, and partly Jacobs U.K.), the text gives the underlying operating margin. The two Renesas entities report in US dollars — their sterling figures are converted and approximate. Figures are approximate — verify any specific figure against the company’s own accounts before relying on it. This is analysis, not financial advice.