If you're a CMO seeking independent expert advice, there's a void.
In an era when marketing has grown more complex, less transparent, and more consequential, a quiet but significant realignment is underway in the advisory world. Mediasense, a London-based consultancy, has appointed Sam Tomlinson as CEO at precisely the moment when billions in advertising spend are poised to shift hands — with at least 27 of the world's top 100 advertisers overdue for agency reviews. The deeper question Tomlinson is asking is not merely who will manage these transitions, but whether an independent voice can finally exist for the CMO the way McKinsey exists for the CEO — a trusted counsel unburdened by commercial conflict.
- A $24 billion wave of media spending — $13 billion already moved, $11 billion actively in play — is reshaping which agencies hold the world's largest advertising accounts.
- At least 27 top-100 global advertisers haven't reviewed their media relationships in over seven years, creating a pressure-cooker dynamic that could release enormous opportunity in the second half of 2026.
- Mediasense's new CEO inherited a firm still one organizational rung below the CMO suite it needs to reach, with a private equity backer quietly approaching the five-year mark where exit planning typically begins.
- Rival consultancy Ebiquity is making nearly identical moves, signaling that the race to become the definitive independent marketing advisor is already competitive and accelerating.
- Both firms insist they recommend agency reviews only as a last resort — a careful positioning that reveals how much their credibility depends on being seen as counselors, not deal-makers.
Sam Tomlinson stepped into the CEO role at Mediasense last week, succeeding Jamie Posnanski, who has returned to the United States. The transition arrives at a loaded moment: Mediasense's private equity backer, Apiary Capital, is nearing the five-year mark on its investment — the horizon at which most PE firms begin considering their exit — while the broader market for agency reviews is building toward what many expect will be a significant surge.
Mediasense has spent recent years expanding through acquisition, most notably absorbing PwC's U.K. marketing and media practice in 2024 — the very team Tomlinson came from. Now he is tasked with positioning the firm to capture a wave of client reviews that industry observers believe will crest in the second half of 2026. The numbers are striking: $13 billion in media spend has already changed agency hands this year, another $11 billion is actively under review, and at least 27 of the world's top 100 advertisers have not run a competitive review in more than seven years.
Tomlinson's ambition is pointed. He wants Mediasense to become the instinctive first call for chief marketing officers seeking independent strategic counsel — the CMO equivalent of what McKinsey is to a CEO or PwC to a CFO. The gap, he argues, is real: agencies carry inherent conflicts of interest, and tech platforms are no different. An expert voice with no stake in the outcome is precisely what the market lacks.
The obstacle is equally clear. Mediasense currently operates closer to marketing procurement and brand teams than to the CMO suite itself. Closing that gap demands senior talent and genuine strategic credibility, not just process management. Tomlinson has assembled a team of veterans and signaled further hiring to come.
Mediasense is not navigating this terrain alone. Ebiquity, its closest rival, is pursuing a nearly identical positioning — from strategy consulting to operating model design to pitch oversight — and its CEO speaks in strikingly similar terms about transformation over transaction. Both firms are careful to frame agency reviews as a last resort, a distinction that matters enormously to their identity as trusted advisors rather than hired guns.
Whether Tomlinson can lift Mediasense from capable operator to indispensable consigliere — and whether Apiary Capital's timeline permits the patient investment that ambition requires — is the unresolved question at the center of this transition.
Sam Tomlinson took over as CEO of Mediasense last week, stepping up from his role managing client relationships. He replaced Jamie Posnanski, who has departed the company and returned to the United States. The timing matters because Tomlinson is inheriting a consultancy at a peculiar inflection point—one where the private equity firm backing it, Apiary Capital, is approaching the five-year mark since its initial investment, a threshold where most PE owners begin plotting their exit.
Mediasense, based in London, is one of the larger advisory firms helping marketers navigate the treacherous terrain of agency relationships. The company has spent recent years absorbing acquisitions, including the U.K. marketing and media operations of PwC in 2024, which is where Tomlinson himself came from. Now he faces the task of positioning the firm to capture what industry observers expect will be a significant wave of client reviews in the second half of 2026. Already this year, $13 billion in media spending has moved between agencies, with another $11 billion currently in active review. At least 27 of the world's top 100 advertisers have not conducted a competitive review of their media accounts in more than seven years—a backlog that, when it breaks loose, will create substantial opportunity for consultancies that can orchestrate those transitions.
Tomlinson's vision for Mediasense is explicit and ambitious. He wants the firm to become the default independent advisor for chief marketing officers, filling a gap he sees in the market. "If you're a CEO and you want advice, you turn to McKinsey or Bain or BCG," he told Digiday. "If you're a CFO, you turn to PwC or KPMG. If you're a CTO, you turn to IBM or Capgemini. But if you're a CMO and you want independent expert advice, there's a void." Agencies can provide expertise, he argues, but their counsel is inherently compromised by their own commercial interests. Tech platforms offer similar conflicts. Mediasense wants to be the firm that gives CMOs advice that is both expert and independent.
The challenge, which Tomlinson acknowledges, is that Mediasense currently operates one level below where it needs to be. The firm has relationships with marketing procurement leaders and brand teams, but not yet with the CMO suite itself. Climbing that organizational ladder requires not just strategy but execution—and talent. Tomlinson says the company has assembled senior leaders including Greg Paull, Shufen Goh, and Ryan Kangisser, veterans from Mediasense and the consultancy R3, who can handle sophisticated client work. He also signaled plans to expand the team further.
Mediasense is not alone in seeing opportunity. Ebiquity, a rival consultancy, is experiencing similar momentum. Its CEO, Ruben Schreurs, described his firm's positioning in strikingly similar language: helping clients transform and grow through everything from strategy consulting to operating model design to pitch management. Both executives emphasized that they advise on reviews only as a last resort, a point that underscores the delicate positioning these firms must maintain—they need to be trusted advisors, not mercenaries.
The broader context is one of mounting complexity and risk in marketing. As one anonymous consultancy head put it, marketing and media have become "more complicated, less transparent, more risky" while agencies themselves have grown harder to manage. Marketing leaders increasingly want an objective partner to help them develop strategy and apply governance to their large marketing investments. This demand is real and growing, but it also means consultancies face intense competition not just for clients but for the senior talent required to serve them credibly.
For Tomlinson and Mediasense, the next phase will test whether a new CEO and a clearer strategic vision can elevate the firm from a capable operator into the kind of trusted consigliere that CMOs instinctively turn to. The market is certainly primed for it. Whether Mediasense can actually reach that level—and whether Apiary Capital's ownership timeline allows for the patient investment required—remains to be seen.
Notable Quotes
Our vision is to be the No. 1 advisor of choice for marketers and their colleagues. If you're a CMO and you want independent expert advice, you can get expert advice from your agencies or tech partners, but that advice is expert but not independent.— Sam Tomlinson, CEO of Mediasense
Marketing leaders want an objective expert partner to help them develop strategies and apply good governance to their large investments in marketing communications.— Anonymous rival consultancy head
The Hearth Conversation Another angle on the story
Why does it matter that Mediasense has a new CEO right now, specifically?
Because the private equity firm backing them is approaching five years of ownership, which is when most PE investors start planning their exit. A new CEO signals they're preparing the business for either a sale or a significant scaling push. The timing also coincides with what could be a very lucrative period for consultancies—billions in media accounts are about to move.
What's the actual gap Tomlinson is trying to fill?
He's saying that when a CMO needs independent strategic advice about their media and marketing operations, there's no obvious place to turn. Agencies have a conflict—they're selling you their services. Tech platforms have the same problem. McKinsey and the big strategy firms don't specialize in marketing. Mediasense wants to be the trusted, impartial advisor in that space.
But doesn't every consultancy say they're independent?
They do, but Tomlinson's point is more specific. He's not claiming independence in the abstract. He's saying that if you're a CMO and you need help evaluating your agency relationships, restructuring your marketing operations, or running a review, you need someone who doesn't have a financial stake in the outcome. That's genuinely rare.
Is Mediasense actually positioned to do this?
Not yet, and Tomlinson admits it. They have relationships with procurement teams and brand managers, but not with CMOs themselves. That's a significant gap. They have the talent—people from PwC and other strong firms—but they need to prove they can operate at that level consistently.
What's driving all these account reviews in the first place?
Marketing has become messier and riskier. Measurement is proliferating but insights arrive too late to act on. Agencies are harder to manage. CMOs are under pressure to prove ROI. So they're looking for help—either to restructure their agency relationships or to get independent perspective on whether their current setup is working. That's creating demand for consultancies.
So this is really about CMOs losing confidence in their agencies?
Not entirely. It's more that the relationship has become more transactional and complex. CMOs want partners who can help them navigate that complexity without a hidden agenda. Whether Mediasense or any consultancy can actually deliver that at scale is still an open question.