How many employees work at O'Halloran & O'Brien?
O'Halloran & O'Brien Ltd. has approximately 403 total employees worldwide as of March 2026, according to Revelio Labs workforce intelligence data. O'Halloran & O'Brien’s total headcount has declined 5.7% from 427 employees in 2023 to 403 in 2026.
Is O'Halloran & O'Brien hiring right now?
Yes, O'Halloran & O'Brien is actively hiring. O'Halloran & O'Brien had 5 active job postings in 2026, a 50.0% increase from 2025 — see job openings & hiring trends.
About O'Halloran & O'Brien’s Workforce
O'Halloran & O'Brien Ltd. is an Engineering and Construction Services company that employs 403 people worldwide as of March 2026. It is the 11th-largest by headcount among its peers. Founded in 1972, the company is headquartered in London, United Kingdom.
O'Halloran & O'Brien's workforce has declined 5.7% from 2023 to 2026, and it is down 2.4% year over year in 2026. The headcount reached a low of 403 in 2026 Q1 before recovering. The vast majority of employees are in the United Kingdom (95.3%), with Romania (0.7%) and Sweden (0.6%) following, and Romania is noted as the fastest-growing location.
O'Halloran & O'Brien's largest groups are Finance and Operations (52.2%), Engineering (24.2%), and Sales and Marketing (23.6%), with Sales and Marketing growing the fastest (up 1%). The median tenure is 4.9 years. The average salary is $65,021, with regional medians of $60,000 in Northern Europe and $25,000 in Eastern Europe.
O'Halloran & O'Brien's hiring activity shows a rising trend, with postings up 50% in 2026 to 5, and new postings per month increasing from 5 in 2023 to 23 in 2026. Sentiment across the workforce is neutral and moving upward.
Sourced from Revelio Labs workforce data.
- Headquarters
- London, United Kingdom
- Founded
- 1972
- Industry
- Engineering and Construction Services
- Employees
- 403
- YoY
- -2.4% (-29)
As of March 2026
O'Halloran & O'Brien workforce metrics
Unlock hiring rate, attrition rate, and 12 additional workforce metrics for O'Halloran & O'Brien. Compare to peers, export the dataset, and access the full quarterly history.
Unlock MetricsO'Halloran & O'Brien Annual Employee Count (2023-2026)
- O'Halloran & O'Brien had 403 employees in 2026, a 2.4% decline (-29) from 2025.
- O'Halloran & O'Brien had 403 employees in 2025, a 3.2% decline (-55) from 2024.
- O'Halloran & O'Brien had 458 employees in 2024, a 0.5% decline (+12) from 2023.
- O'Halloran & O'Brien had 446 employees in 2023, a 1.4% decline (+17) from 2022.
O'Halloran & O'Brien's total workforce has declined from 427 employees in 2023 to 403 in 2026. O'Halloran & O'Brien's headcount peaked at 467 in 2024.
O'Halloran & O'Brien Ltd. quarterly employee count
| Year | Qtr | Employees | YoY Change | YoY % |
|---|---|---|---|---|
| 2026 | Q1 | 403 | -29 | -2.4% |
| 2025 | Q4 | 403 | -55 | -3.2% |
| 2025 | Q3 | 406 | -61 | -4.2% |
| 2025 | Q2 | 412 | -50 | -4.6% |
| 2025 | Q1 | 432 | -27 | -2.4% |
| 2024 | Q4 | 458 | +12 | -0.5% |
| 2024 | Q3 | 467 | +36 | +1.0% |
| 2024 | Q2 | 462 | +35 | +2.0% |
| 2024 | Q1 | 459 | +41 | +2.0% |
| 2023 | Q4 | 446 | +17 | -1.4% |
| 2023 | Q3 | 431 | -1 | -2.1% |
| 2023 | Q2 | 427 | -4 | -0.8% |
See O'Halloran & O'Brien's complete headcount history, including quarterly breakdowns.
Get the DataO'Halloran & O'Brien Employee Count by Country and Region (2026)
The United Kingdom accounts for the largest share of O'Halloran & O'Brien's global workforce with approximately 95% of total employees, followed by Romania and Sweden.
O'Halloran & O'Brien employees by country
| Country | Employees | % of Total | YoY % |
|---|---|---|---|
| United Kingdom | 383 | 95.3% | -1.6% |
| Romania | 3 | 0.7% | +0.0% |
| Sweden | 2 | 0.6% | +0.0% |
| South Africa | 2 | 0.5% | +0.0% |
| Israel | 2 | 0.4% | +0.0% |
| Switzerland | 2 | 0.4% | +0.0% |
| Moldova | 2 | 0.4% | +0.0% |
| Morocco | 1 | 0.3% | +0.0% |
| Germany | 1 | 0.3% | +0.0% |
| Poland | 1 | 0.3% | +0.0% |
Drill into city-level data, hiring trends by region, and historic geographic shifts.
Unlock Geographic DataO'Halloran & O'Brien Employee Count by Department (2026)
O'Halloran & O'Brien's largest employee groups are Finance and Operations (52.2%), Engineering (24.2%), and Sales and Marketing (23.6%).
O'Halloran & O'Brien employees by department
| Department | Employees | % of Total | YoY % |
|---|---|---|---|
| Finance and Operations | 204 | 52.2% | -1.9% |
| Engineering | 94 | 24.2% | -3.5% |
| Sales and Marketing | 92 | 23.6% | +1.0% |
Compare O'Halloran & O'Brien's department mix to industry peers.
See Full DataO'Halloran & O'Brien Employee Salary by Region (2026)
O'Halloran & O'Brien's average employee salary is $65,021 globally. Employees in Northern Europe receive the highest compensation. Pay is lowest in Eastern Europe, at a median of $25,000.
O'Halloran & O'Brien median employee salary by region (USD)
| Region | Median Salary |
|---|---|
| Northern Europe | $60,000 |
| Eastern Europe | $25,000 |
Unlock salary by role, level, and city — and compare to O'Halloran & O'Brien's industry peers.
Unlock Salary DataO'Halloran & O'Brien Job Openings and Hiring Trends (2023-2026)
- O'Halloran & O'Brien had 5 active job postings in 2026, a 50.0% increase (-2) from 2025.
- O'Halloran & O'Brien had 7 active job postings in 2025, a 35.3% decline (-3) from 2024.
- O'Halloran & O'Brien had 10 active job postings in 2024, a 75.0% decline (-12) from 2023.
- O'Halloran & O'Brien had 22 active job postings in 2023, a 166.7% increase from 2022.
- Hiring velocity in 2026: 23 new roles/month, up from 17 in 2025 and 28 in 2024.
O'Halloran & O'Brien's hiring is accelerating: active job postings rose 50.0% in 2026 to 5, with new postings per month climbing from 5 in 2023 to 23 in 2026.
Track new postings per month, role-level demand, and hiring velocity vs. peers.
Unlock Hiring DataO'Halloran & O'Brien Employee Sentiment (2026)
Revelio Labs tracks employee sentiment across O'Halloran & O'Brien's workforce based on public professional data. Overall sentiment is neutral and has improved year over year in 2026.
Overall
Unlock the full sentiment breakdown by department, tenure, and trend over time.
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Frequently Asked Questions About O'Halloran & O'Brien
- How fast is O'Halloran & O'Brien growing?
- In 2026, O'Halloran & O'Brien's headcount shrank 2.4% to 403 employees, down from 432 in 2025.
- Where are O'Halloran & O'Brien employees located?
- Most O'Halloran & O'Brien employees are based in the United Kingdom (95.3% of headcount), followed by Romania and Sweden.
- What is the average salary at O'Halloran & O'Brien?
- The average employee salary at O'Halloran & O'Brien is approximately $65k per year.
- How many people does O'Halloran & O'Brien hire per year?
- In 2026, O'Halloran & O'Brien opened roughly 276 new roles — about 23 per month.
- When was O'Halloran & O'Brien founded and where is it headquartered?
- O'Halloran & O'Brien was founded in 1972 and is headquartered in London, United Kingdom.
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