Sarah was your best employee. Reliable, personable, productive and your clients loved her.
So when the team leader position opened up, promoting her seemed obvious. She'd earned it. She deserved the recognition.
And surely someone that good at their job would be equally good at managing others?
Eighteen months later, Sarah resigned. So did two of her former teammates. Business hadhad slowed. And you were left wondering what went wrong.
This story plays out in organisations across the UK every single day.
And the numbers behind it should alarm anyone responsible for people development.
According to data from the OECD (Organisation for Economic Co-operation and Development), there are approximately 2.4 million "accidental managers" operating in the UK right now.
These are people promoted into management based on technical ability, without the training to actually lead a team.
The cost to employers?
The OECD estimates this costs the UK economy approximately £84 billion per year in lost productivity.
Let that sink in. We're not talking about a minor inefficiency. We're talking about a systemic failure.
Research from the Chartered Management Institute (CMI)—the UK’s leading professional body for management—makes the scale of the problem brutally clear.
Their landmark study found that 82% of managers in the UK enter their roles without any formal management or leadership training.
They're handed responsibility for other people's careers, performance, and wellbeing—and left to figure it out on their own.
The "Peter Principle"—the idea that people get promoted to their level of incompetence—used to be a joke.
But recent experimental research from the University of Texas has provided hard evidence that it is very real.
In controlled studies, researchers found that when organisations promoted their best performers into management roles (rather than selecting for management aptitude):
Those promoted individuals produced 28% less output than workers who had tested well for leadership tasks.
Their teams earned 33% lower profits.
The logic seems counterintuitive at first. Why wouldn't your best performer make a great manager?
Because management requires an entirely different skill set.
The abilities that made Sarah exceptional at sales—competitive drive, individual focus, technical expertise—are often the opposite of the abilities needed to develop others, delegate effectively, and build team cohesion.
Being brilliant at doing the work doesn't prepare you for the work of enabling others to be brilliant.
When you promote someone without support and they struggle, the costs multiply in ways that rarely show up on a balance sheet.
You lose the manager. Thrown into a role they weren't equipped for, many eventually leave.
Replacing a mid-level manager costs upwards of £30,000 when you account for recruitment, training, and lost productivity.
You lose their team. 31% of UK workers have left a job because of a negative relationship with their manager.
When your newly promoted star struggles, the people who used to work alongside them—and now work underneath them—feel it directly.
You lose the contribution they used to make. Here's the cruel irony: by promoting your best performer, you've removed them from the role where they excelled. If they then struggle as a manager, you've lost their original contribution entirely—and gained nothing in return.
The CIPD (Chartered Institute of Personnel and Development) puts it clearly: management positions are often seen as a "reward" for good performance, rather than completely different jobs requiring a people-oriented skillset.
Top individual contributors typically thrive on personal achievement.
They are motivated by being the expert.
Management requires the opposite orientation—finding satisfaction in others' success and stepping back so team members can grow.
This isn't a criticism of those individual contributors. They are often as frustrated as anyone by the mismatch.
They accepted a promotion because that's what career progression looked like, only to find themselves doing work they weren't prepared for.
The solution isn't to stop promoting talented people.
It's to stop promoting them without proper support.
Managers with formal training are significantly more likely to trust their team and create environments where people feel valued.
But what does "proper support" actually mean?
Organisations that invest in management development see measurable returns.
Research shows that companies with highly trained managers achieve 31% lower turnover than those using traditional approaches.
Good managers also drive engagement.
Gallup data consistently shows that the single biggest variance in team engagement scores is the quality of the manager.
Employees whose manager involves them in goal setting are four times more likely to be engaged.
Senior leaders set strategy.
But it's first-line managers who translate that strategy into reality.
When those managers are struggling—promoted without preparation, learning by trial and error—everything downstream suffers.
The question isn't whether you can afford to invest in first-line management development. The question is whether you can afford not to.
Every high performer you promote without preparation is a gamble with your best talent—both the person being promoted and the team they're now responsible for.
The BCF Group's First Line Management programme is designed specifically for people making the transition from individual contributor to team leader.
During the programme, delegates develop the practical skills that make the difference between struggling and succeeding in that critical first management role.
We also offer ILM Level 3 qualifications for those wanting a formally recognised pathway into leadership.
Get in touch to discuss how we can help your new managers thrive—not just survive.