B2B Ads Consultant London: The Ultimate Hiring Guide

I get it. You're a B2B founder in London, you're trying to grow, and you know paid ads could be the answer. But trying to find a consultant who actually knows what they're doing feels like a total nightmare. The market is flooded with agencies and freelancers, all promising the world, and it’s impossible to know who to trust. Most of them talk a good game but have never managed a serious B2B budget in their life.

The truth is, most businesses get burned because they focus on the wrong things. They look for a flashy office near Old Street or a big agency name, assuming that equals results. It doesn't. You're not hiring an agency; you're buying expertise. Your one and only job is to find concrete proof of that expertise before you hand over a single pound. This guide is my attempt to give you a proper framework for doing exactly that, based on years of being on both sides of the table.

So, what makes a case study actually useful?

First thing's first: you need to see their track record. And I don't mean a glossy PDF with logos on it. I mean detailed case studies. But even then, you need to know what you're looking for. A lot of agencies will show you fluff metrics like 'impressions' or 'reach'. I remember one campaign we worked on that got "10 Million Views" for a luxury brand. Sounds great, but it tells you nothing about whether it actually sold anything. It's a vanity metric, designed to impress people who don't know any better.

What you need to look for is proof they can drive business outcomes. Dig into their B2B case studies. Are they showing you Cost Per Lead (CPL)? Return On Ad Spend (ROAS)? Are they talking about qualified leads, not just cheap form fills? For instance, one campaign we worked on hit a $22 CPL for senior B2B decision makers on LinkedIn, which is a solid result for that platform. For another B2B SaaS client, we took their Cost Per User Acquisition from a painful £100 down to just £7. Those are the kind of numbers that matter. If a consultant can't show you results like that, for businesses at least vaguely similar to yours, you should be very skeptical.

A good case study shouldn't just show the final numbers; it should tell a story. What was the client's problem? What was the strategy they implemented? Why did it work? It should give you a real sense of their thinking process. A bad case study is all sizzle and no steak.

How to run the initial call so you get real answers

Okay, so you've found a consultant with some decent-looking case studies. The next step is the initial call or consultation. This is your chance to really probe their expertise. Don't let them just run through a sales presentation. You need to come prepared with questions that will reveal whether they actually know their stuff or are just repeating a script.

One of the biggest red flags is someone who makes promises. Tbh, in paid advertising, you can't really promise anything. The market changes, platform algorithms change, and it's impossible to predict exactly how ads will perform. A real expert will talk about 'expected ranges' and 'benchmarks' based on their experience, not 'guaranteed results'. They should sound cautiously optimistic, not like a used car salesman.

Here are a few questions I'd be asking:

"Based on my business, which ad platform would you prioritise and why?"
This is a basic but telling question. For most B2B businesses in London, especially in tech or finance, the answer will likely be a mix of Google Search and LinkedIn. Google Search is brilliant for capturing people who are actively looking for a solution right now (e.g. searching "AI implementation service London"). LinkedIn is unmatched for targeting specific decision-makers at specific companies, like the Head of Engineering at a FTSE 250 firm. If they just say "Facebook" without a very, very good reason, they probably don't have much B2B experience. Getting this right is so important that we wrote a whole guide to using LinkedIn ads for London B2B founders.

"What's a realistic Cost Per Lead we might expect in the UK market for our industry?"
This tests their real-world experience. They won't be able to give you an exact number, but they should be able to provide a sensible range. For B2B leads in developed countries like the UK, a lead from a social media campaign could be anywhere from £15 to £75 or more, depending on how qualified they need to be. For highly specific search keywords, it can be even higher. If they pluck a ridiculously low number out of the air, they're probably just telling you what you want to hear. A good consultant manages your expectations realistically.

"Our last campaign got clicks but no conversions. What would be the first three things you'd investigate?"
This is a killer question. A novice will talk about changing the ad copy or the button colour. An expert will immediately start asking about the offer, the landing page, and the audience targeting. They'll know that conversions fail because of a disconnect between the ad, the page, and the user's intent. They'll ask about your sales cycle, your value proposition, and who you were targeting. Their answer will show you whether they think like a tactician (fiddling with ads) or a strategist (fixing the entire funnel).

This first call is absolutely critical. It’s the first and most important step in the process, which is why we break it down further in our complete UK guide to hiring a paid ads consultant. Don't be afraid to ask tough questions. You're not just hiring someone to click buttons; you're looking for a strategic partner.

Figuring out the budget: Ad spend vs. fees in London

This is where founders often get stuck. How much should you actually spend? It's a two-part question: your ad spend (the money that goes to Google, LinkedIn etc.) and the consultant's management fee.

For ad spend, a good starting point for a B2B business looking to test the waters is usually around £1,000 to £2,000 per month. But honestly, that's just a finger in the air. The real calculation should be based on your goals. How many qualified leads do you need each month to hit your growth targets? And what's a realistic CPL? If you need 20 leads and your average CPL is £75, you need an ad spend of £1,500. It's simple maths, but so many people just pick a random number they feel comfortable with.

To make this a bit more tangible, I've put together a simple calculator. Play around with the sliders to see how your lead goals and the cost per lead affect your required ad spend. It’s a simple tool, but it can help you move from guesswork to a data-informed budget.

As for management fees, they vary wildly in London. You'll find freelancers charging a few hundred quid a month and big agencies charging tens of thousands. Generally, you'll see a few models:

• -> Flat Retainer: A fixed fee each month. This is common and helps with budgeting. Expect anything from £1,000 to £5,000+ per month for a good consultant or small agency.
• -> Percentage of Ad Spend: Usually 10-20%. This can work, but it can also incentivise the consultant to just spend more money, not necessarily more effectively.
• -> Performance-Based: A lower retainer plus a bonus for hitting certain targets (e.g., a fee per qualified lead). This can be great for aligning incentives but is less common for new clients.

Don't just go for the cheapest option. A cheap consultant who wastes your ad spend is far more expensive than a professional one who costs more but delivers a positive ROI. The London market commands a premium, but with that, you should expect a higher level of strategic thinking. Understanding the different ways you might be charged is really important, and there's a lot more nuance to it; if you're interested, we have a detailed breakdown of London ad agency pricing models for founders.

The definite red flags that mean you should run a mile

Over the years, I've seen some real horror stories. Founders who've been locked into long contracts with agencies delivering nothing, or who've had their ad accounts completely messed up by someone who didn't know what they were doing. To save you some of that pain, here are the biggest red flags to watch out for. If you see any of these, just walk away.

1. The Hard Sell and Guarantees. As I mentioned, anyone who guarantees results is either naive or dishonest. An expert knows there are too many variables. They should be confident in their process, not in a specific outcome. If the conversation feels more like a high-pressure sales pitch than a strategic discussion, that's a bad sign.

2. All B2C Experience. Running ads for a £20 t-shirt is a completely different world from generating a qualified lead for a £50,000 software contract. The sales cycles are different, the platforms are different, the messaging is different. If all their case studies are for e-commerce or consumer apps, they will likely struggle with the complexities of B2B. You need someone who understands long sales cycles and how to nurture a lead from a click to a signed contract. Without that experience, they'll likely struggle to calculate a proper return on investment for your B2B paid ads.

3. The "Secret Sauce" Obsession. Be wary of anyone who talks about a "secret formula" or "proprietary algorithm". Good paid advertising isn't magic. It's a methodical process of research, testing, analysis, and optimisation. A good consultant will be transparent about their process and what they're doing. Someone who hides behind jargon and buzzwords is probably hiding a lack of real substance.

4. The Reference Trap. This is a bit of a contrarian one. Some founders insist on speaking to a consultant's current clients. Tbh, if someone asks us for references after they've already seen our detailed case studies and we've given them a free, in-depth strategy review, it's an instant red flag for us. It signals a fundamental lack of trust from the very beginning, and that's a terrible foundation for a partnership. A consultant's work and their strategic insights should speak for themselves. If you've done your due diligence on their case studies and grilled them on a call, you should have all the proof you need.

Spotting these warning signs is a huge part of the battle. It's not just about finding someone good; it's about actively avoiding the bad ones who can do real damage. To help founders, we've actually built out a complete vetting framework for finding a B2B ad agency in London that goes into more detail on what to look for.

I've found someone – now what? Setting up for success

Congratulations, you've vetted a consultant, agreed on a fee, and you're ready to go. But the work isn't over. The first three months of any new advertising engagement are critical. This is where you set the foundation for long-term success, and it's essential to have the right expectations.

You are not going to see a 10x ROAS in the first week. B2B paid advertising, especially in a competitive market like London's tech scene, is a long game. It takes time to gather data, test audiences, refine messaging, and figure out what truly works. A good consultant will spend the first month doing deep research, setting up tracking properly, and launching initial test campaigns. You're looking for early positive signals, not a flood of sales.

These early signals could be:

• -> A healthy Click-Through Rate (CTR) on your ads, showing the message is resonating.
• -> A reasonable Cost Per Click (CPC) for your industry.
• -> Some initial leads coming through, even if they're not all perfect.
• -> Most importantly, clear communication and reporting from your consultant about what they're testing and what they're learning.

The process is iterative. You test, you learn, you optimise, you scale. Anyone who promises a "set it and forget it" solution doesn't understand how this works. It requires ongoing effort and a strong partnership between you and your consultant. You know your business and your customers better than anyone; they know the ad platforms. Success comes from combining that knowledge.

Your step-by-step plan for finding the right consultant

I know this is a lot to take in, so I've boiled it down into a simple, actionable plan. If you follow these steps, you will dramatically increase your chances of finding a great consultant and avoiding the tyre-kickers. This is the main advice I have for you:

Finding the right person won't be easy, especially in a city as packed with agencies as London. But it's far from impossible if you approach it with a clear framework and a healthy dose of skepticism. Stop looking for a "paid ads person" and start looking for a strategic growth partner who can show you, not just tell you, that they know how to turn ad spend into actual revenue.

Whether you're a SaaS startup in Shoreditch trying to choose between a consultant or a full agency, or a more established firm in Canary Wharf looking to find experts that can drive qualified B2B leads, the principles are the same. Do your homework, ask the hard questions, and trust the evidence of their past work above all else.

If you've read this far and you're feeling a bit overwhelmed, that's normal. This stuff is complex. If you're a B2B business in London and you'd rather just talk to an expert, you might want to consider some outside help. We offer a completely free, no-obligation 20-minute strategy session where we'll take a look at your business, your goals, and give you some honest, actionable advice you can take away and use. It's a great way to get a second opinion and a taste of the kind of expertise you should be looking for. Feel free to book a call if that sounds helpful.

Hope this helps!