What a senior in-house hire actually costs, with the sums shown

The in-house-versus-agency argument is usually run on a salary number against a retainer number, which is the one comparison guaranteed to mislead. A salary is not what an employee costs, and a retainer is not what an agency delivers. Both sides of that sum need unpacking before it means anything.

Start with the market rate. A 2026 recruiter benchmark for London and the South East puts a Head of Paid Media at £75,000 to £100,000, averaging £85,000; a Senior PPC Manager at £60,000–£80,000; a Performance Marketing Manager at £45,000–£70,000; a Creative Director averaging £100,000.^[1] Those are practitioner figures from briefs taken and placements made, not a survey — no sample size is published, so treat them as a benchmark rather than a statistic.

For a statistical anchor, the ONS Annual Survey of Hours and Earnings — a 1% sample of PAYE records — puts the UK median gross annual pay for marketing, sales and advertising directors at £94,135, rising to £114,014 in London.^[3]

Geography moves this a long way. The same recruiter's South West guide averages a Head of Paid Media at £55,000 against London's £85,000 — a £30,000 swing for the same title and the same method.^[2] If you can hire outside London, do the sums again with your own numbers; several of the conclusions below flip.

Take the £85,000 Head of Paid Media and add the costs the employer carries by law:

So the statutory floor is about £98,300 — roughly £8,200 a month — and that is before recruitment fees (typically a percentage of first-year salary), before software, before a laptop, before any bonus, and before the salary of whoever manages them.

Here's the part that decides it. One senior hire is one person's throughput. They are excellent at judgement, strategy and knowing which test matters — and they are one pair of hands for production.

Run the replacement-rate arithmetic: the creatives you need per week is how many you want live divided by their effective life in weeks. A brand holding twenty live creatives on a four-week life needs five new ones a week, permanently. A single strategic hire will not produce that alongside managing spend, and hiring the designer to sit beside them starts the whole calculation again at a second salary.

This is why the in-house question isn't really about cost per hour. It's about whether one person's output clears your consumption rate.

Agencies deserve the same scrutiny. Two structural facts are worth knowing before you compare.

First, the percentage-of-spend model puts your agency's revenue on the wrong side of your best decision. If spending less is right for your margin, a percentage-fee agency has a structural reason never to be the one who says so. That's not an accusation of bad faith; it's an incentive worth naming out loud.

Second, the industry is smaller and less stable than its pitch decks suggest. A 2025 survey of 376 agency people — opt-in, mostly North American, mostly firms under 25 people — found a quarter said their typical client engagement lasts less than twelve months, and only 14% felt their own pipeline was healthy.^[6] Meanwhile, on the client side, US industry bodies report average client-agency tenure at around seven years, more than double the 3.2 years reported in 2016 — but with integrated relationships at 7.3 years against media-only at 3.7.^[7] Long, stable relationships exist; they're concentrated at the top end, and the churn lives where most DTC brands actually buy.

Set against ~£98,300 statutory floor for one senior hire, plus a three-to-six-month gap, plus a production ceiling of one person:

• Under ~£3k/mo on ads: none of the above. The maths doesn't support an agency or a hire, and a founder with taste and modern tools will outrun both. We say the same on our comparison page.
• £5k–50k/mo, no in-house creative: the bracket where the replacement rate exceeds what one hire produces but doesn't yet justify a team. This is the gap productised creative exists for — and it's the bracket we built for, so weigh that.
• Sustained high volume with creative as your core weapon: in-housing wins, if you can hire senior, absorb the ramp, and retain them. Three conditions, and the third is where in-house creative teams most often quietly fail.
• Any bracket, if you need one thing built well once: a freelancer, and no ongoing cost at all.

The number that decides it isn't the salary or the retainer. It's your replacement rate against the throughput of whatever you're buying. Compute that first and the rest of the comparison mostly answers itself.