Part-Time HR Director for Scale-Ups: A UK Founder's Guide

TL;DR

A part-time HR director for scale-ups gives a fast-growing business senior people leadership — hiring plans, organisation design, reward, culture and employment law compliance — for one to three days a week. With talent and leadership a top-three growth barrier for 55% of UK scale-ups, and unfair dismissal rights moving to six months' service from 1 January 2027, many scale-ups need HR director judgement well before they can justify a full-time hire.

Last updated: 6 November 2026

A part-time HR director for scale-ups solves a problem that growth creates faster than most founders expect. The ScaleUp Institute's Annual Review 2025 found that 55% of UK scale-ups rank access to talent and leadership among their top three barriers to growth, and one in three business leaders rate it as the single biggest barrier.

At 20 people, the founder can know everyone and fix problems informally. At 60 or 120, informal stops working: managers are new to managing, pay has drifted, hiring is reactive and the employment law exposure is real. That is the point where HR director experience starts paying for itself.

This guide focuses on the scale-up stage specifically. For a general overview of the role, see our guide to what a part-time HR director does.

Why scale-ups need HR leadership earlier than they think

Scale-ups usually add HR capacity from the bottom up: an office manager handles contracts, then an HR administrator or outsourced payroll is added. What is missing is someone who designs the people side of the growth plan.

• Hiring at pace — turning a revenue plan into a realistic hiring plan, with roles, levels, timing and budget.
• First-time managers — promoted specialists who need clear expectations, training and support.
• Pay and progression — a simple framework so pay decisions stop being one-off negotiations.
• Culture under strain — keeping what made the early team work as new people arrive.
• Compliance — contracts, policies and processes that keep up with fast-changing employment law.
• Investor scrutiny — people data, key-person risk and retention that stand up in due diligence.

Employment law changes raise the stakes for scale-ups

The Employment Rights Act 2025 is reshaping the rules for growing employers. According to GOV.UK, from 1 January 2027 the qualifying period for protection against ordinary unfair dismissal falls from two years to six months, and the cap on compensatory awards for unfair dismissal is removed. Acas confirms that the time limit for most employment tribunal claims increased from three months to six months on 1 October 2026.

For a scale-up hiring dozens of people a year, that changes how recruitment, probation and performance management need to work. Probation reviews have to be real, early concerns documented and managers trained to handle difficult conversations properly. A part-time HR director puts those foundations in place before they are tested. That includes reviewing contracts and policies, setting clear probation milestones, training managers to give honest feedback early, and making sure every dismissal or non-renewal follows a fair, documented process. Getting this right before January 2027 is far cheaper than defending an uncapped tribunal claim afterwards.

What a part-time HR director for scale-ups does

A good part-time HR director starts by linking the people plan to the business plan: how many people, in which roles, by when, and at what cost. They then build the essentials in a sensible order — contracts and policies that are fit for growth, a structured hiring process, onboarding that gets people productive quickly, and a probation and performance process managers can actually use.

From there they shape organisation design as teams split and new leadership layers appear, introduce a pay and progression framework, and set up simple people metrics such as time to hire, early attrition and engagement. They coach the founder and leadership team on people decisions, and manage the sensitive cases that can otherwise consume a founder's week. Just as importantly, they help the founder let go of people decisions that no longer need to sit with them, so the leadership team owns its own hiring and performance conversations.

Picture a 70-person UK software scale-up planning to reach 150 people within two years after a funding round. Hiring is ad hoc, three new team leads have never managed before and two recent leavers have raised grievances. A part-time HR director from our bench builds a costed hiring plan, introduces a structured interview process and a proper probation review, trains the new managers and puts a simple pay framework in place. Early attrition falls, hiring speeds up and the board gets a monthly people dashboard for the first time.

Part-time HR director or full-time hire?

Most scale-ups between 30 and 200 people do not need a full-time HR director — they need the experience of one, applied for a few days a week, with HR administration handled by a coordinator or outsourced provider. A part-time HR director for scale-ups typically works one to three days a week, flexing up during restructures, rapid hiring phases or a funding round.

As the business approaches 200 to 300 people, or where people risk is unusually high, a permanent HR director becomes easier to justify — and a part-time HR director can help define the role and recruit them. Our guide to HR outsourcing versus a fractional HR director compares the models, and our fractional HR director services explain how we work with scale-ups.

Frequently asked questions

Ready to build the people side of your growth plan?

Leadership Services gives UK scale-ups access to a bench of 500+ senior directors, including HR directors who have built hiring plans, management teams and people frameworks for fast-growing businesses. Engagements start from £1,795 per month, begin within one week and have no long-term tie-ins — get in touch and we will respond the same working day.