B2B Paid Ads: The London Agency Selection Guide

I see this question a lot. You're a founder in London, you need qualified leads for your B2B business, and you're drowning in a sea of agencies that seem more interested in talking about brand awareness and TikTok trends than your sales pipeline. It's a genuine problem. The vast majority of agencies, especially the big flashy ones in Central London, built their entire model on B2C marketing – quick sales, emotional triggers, and massive volume. Applying that logic to a considered B2B purchase with a six-month sales cycle is like using a sledgehammer to perform surgery. It's messy, expensive, and it won't work.

Finding a reliable B2B paid ads partner in London isn't about finding the agency with the fanciest office or the most impressive client logos. It's about finding a team of specialists who think like commercial directors, not just marketers. They need to understand the maths of your business, the deep-seated pain points of your customers, and the nuances of platforms like LinkedIn and Google Search for lead generation. Let's cut through the noise and talk about how you actually find one.

So why are most agencies in London so bad at B2B?

The core of the issue is a fundamental misunderstanding of the B2B buyer. A B2C purchase is often an impulse. You see a nice pair of trainers on Instagram, you like the colour, you buy them. The whole process takes five minutes. A B2B purchase is a calculated investment. Someone's job might be on the line. The decision involves multiple stakeholders—the user, the finance director, the CTO, the head of legal. It can take months of meetings, demos, and security reviews.

Most agencies just aren't set up for that. Their teams are trained to optimise for clicks, impressions, and maybe a quick online sale. They'll take your money and plough it into a 'brand awareness' campaign on Facebook. As I've said before, this is just paying the platform to find you an audience of non-customers. The algorithm is told to find the cheapest eyeballs, which invariably belong to people who are the least likely to ever buy complex B2B software or a high-ticket service. You'll get a lovely report full of big numbers, but your finance director will correctly point out that your sales haven't moved an inch.

They treat B2B leads as a numbers game, aiming for volume over quality. They'll celebrate getting you 100 leads at £50 each, without questioning if any of them are from the right comapnies or have any purchasing power. A true B2B specialist knows that one lead from a Chief Technology Officer at a target account, even if it costs £300, is infinitely more valuable than 100 leads from interns at micro-businesses. This is a mindset shift that most agencies just haven't made, and it's why so many B2B founders end up feeling burned.

How can you spot a true B2B specialist from the first conversation?

It all comes down to the questions they ask. A B2C-focused agency will ask about your brand, your target demographics, and your social media presence. A genuine B2B expert will go straight for the jugular: your customer's pain. They know your Ideal Customer Profile (ICP) isn't a job title and an employee count; it's a 'nightmare scenario'.

Forget "we're targeting Marketing Managers in finance companies with 100-500 employees". That's uselessly broad. A specialist will dig deeper. They'll ask questions like:

• -> What keeps that Marketing Manager awake at night? Is it the fear of presenting a report to the board with rubbish ROI figures?
• -> What's the specific, career-threatening problem they're facing that your product solves? Are they terrified of a competitor eating their lunch because their tech stack is outdated?
• -> What happens if they do nothing? Do they miss their targets and lose their bonus? Does their department get seen as a cost centre?

This line of questioning is the single biggest indicator that you're talking to someone who gets B2B. They're not trying to sell a product; they're trying to understand a problem so they can position your service as the only logical solution. They're already thinking about ad copy that will stop a busy executive mid-scroll because it speaks directly to their biggest professional fear.

What's the one number you MUST know before hiring anyone?

Before you have a single conversation with an agency, you need to do some basic maths. The most important metric in your entire business is your Customer Lifetime Value (LTV). This number dictates how much you can sustainably spend to acquire a new customer. Any agency that doesn't ask you for this, or help you calculate it, is flying blind.

The calculation is simple. You need three figures:

1. Average Revenue Per Account (ARPA): How much a customer pays you per month.
2. Gross Margin %: Your profit margin on that revenue.
3. Monthly Churn Rate %: The percentage of customers you lose each month.

The formula is: LTV = (ARPA * Gross Margin %) / Monthly Churn Rate

So, if a customer pays you £1,000 a month, your gross margin is 75%, and you lose 2% of your customers each month, your LTV is (£1,000 * 0.75) / 0.02 = £37,500. This means each new customer is worth £37,500 in gross margin to your business over their lifetime. A healthy business model aims for at least a 3:1 LTV to Customer Acquisition Cost (CAC) ratio. In this case, you can afford to spend up to £12,500 to acquire a single new customer. If your sales team converts 1 in 10 qualified leads, you can afford to pay up to £1,250 for one of those leads. Suddenly that £250 CPL from a highly targeted LinkedIn Ads campaign in London doesn't seem so expensive.

This calculation is your power. It stops you from being seduced by agencies promising ridiculously cheap leads and helps you focus on what actually matters: profitable growth. To make it easier, I've built a calculator for you below.

What should their case studies and strategy actually look like?

When you're vetting an agency, ask to see their case studies. But don't just look at the logos. You need to scrutinise them. A bad case study talks about impressions, clicks, and follower growth. A good B2B case study talks about the only things that matter: qualified leads, cost per qualified lead, sales pipeline generated, and ultimately, revenue. I've worked on B2B SaaS campaigns where we've generated thousands of signups and trials, for example, one where we got 4,622 registrations at just $2.38 each for a B2B software client using Meta Ads. That's a meaningful result because it's tied directly to a business action, not just a vanity metric.

You also need to look at the platforms they use. If an agency's case studies are all for ecommerce brands on Instagram and Pinterest, they are probably not the right fit. For most B2B companies in London, the workhorses are going to be Google Search and LinkedIn Ads.

• -> Google Search Ads: This is for capturing intent. When a Head of Finance in Canary Wharf searches for "new accounting software for scale-ups," you need to be there. A good agency will show you how they do keyword research based on problems, not just product names. One campaign we worked on for a client in the recruitment space reduced their CPA from £100 down to just £7 by refining their Google Ads strategy alongside their Meta ads. It's about precision.
• -> LinkedIn Ads: This is for creating demand. You can target with incredible specificity – job title, company size, industry, even specific company names. A skilled agency can get your message in front of the exact decision-makers you need to reach. But it's expensive, so the strategy has to be spot on. We've managed campaigns that achieve a CPL of around $22 for senior B2B decision-makers, which is highly efficient for the platform.

Finally, look at their strategic recommendations. If their first suggestion is "let's get you to request a demo," be very wary. As I've said many times, the 'Request a Demo' button is one of the worst calls to action in B2B marketing. It's high-friction and low-value for a busy prospect. A smart agency will help you develop a better offer – something that provides immediate value. This could be a free, automated audit tool, a benchmark report for their industry, or a short, high-value video course. For us, it's a completely free 20-minute strategy session where we audit an ad account. You solve a small problem for free to earn the right to solve the big one. An agency that understands this is an agency worth talking to. If you are a founder looking to hire an agency, I've got another guide you should check out that goes into a bit more detail on how to actually vet ad experts.

The London B2B Agency Scene: Who are you really dealing with?

The agency landscape in London can be confusing. Broadly speaking, you'll encounter three main types:

1. The Soho Giants: These are the big, established network agencies with glass-fronted offices and awards lining the walls. They work with massive corporate clients and charge a fortune. The problem for a startup or SME is that you'll likely be a very small fish in their very large pond. The senior partner who sells you the dream won't be the person running your campaigns; it'll be a junior account manager who is learning on your dime. They're often slow, bureaucratic, and stuck in old ways of thinking.

2. The Shoreditch Specialists: Clustered around the "Silicon Roundabout," you'll find smaller, often founder-led specialist agencies. These are often your best bet. They live and breathe B2B tech and services. They're agile, commercially-minded, and their reputation is built on delivering actual results, not just schmoozing clients. Their overheads are lower, and you're much more likely to be working directly with an experienced practitioner. This is the category I'd say we fall into. We focus purely on paid ads and know what it takes to generate leads that turn into revenue.

3. The Remote Experts: In today's world, a London address means less than ever. Some of the best B2B advertising talent doesn't want to commute into the city every day. These agencies or consultants might be based elsewhere in the UK or even abroad, but they have deep, provable expertise in your niche. Don't discount someone just because they don't have an EC2 postcode. Expertise is far more important than proximity, especially when it comes to the highly specialised world of London B2B paid advertising.

What red flags should make you walk away immediately?

As you go through your search, keep an eye out for these massive red flags. If you see any of them, politely end the conversation and move on.

• -> Guaranteed Results: "We guarantee you 50 qualified leads in your first month!" Nobody can guarantee results in paid advertising. There are too many variables. This is a sales tactic used by people who are desperate for your business. It signals inexperience and, frankly, dishonesty.
• -> Long-Term Contracts From Day One: A confident agency will be happy to start with a 3-month trial period or a pilot project. They know they can prove their value in that time. Anyone demanding a 12-month commitment upfront is locking you in because they're afraid you'll leave once you see the poor results.
• -> Vague, Jargon-Filled Strategy: If they can't explain their strategy in plain English, they don't have one. Be wary of talk about "proprietary AI tools" or "synergistic multi-channel funnels." Ask them to be specific: "What audiences will you target on LinkedIn? What keywords will you bid on in Google? What will the ad copy say?" If they can't answer, they're bluffing.
• -> The Bait and Switch: You have a great call with a charismatic, experienced director who clearly knows their stuff. You sign the contract. Then you're handed over to a 22-year-old account manager for your onboarding call. This is a classic move from larger agencies. Insist on knowing exactly who will be working on your account day-to-day and what their experience is.

This is the main advice I have for you:

Finding the right B2B paid ads agency in London is a challenge, but it's not impossible. It requires you to be disciplined in your vetting process and to focus on the right things. Here is a summary of the framework you should follow.

Choosing an agency is a big decision, and the right partner can be truly transformative for your business. The wrong one can set you back six months and tens of thousands of pounds. By arming yourself with the right questions and the right financial benchmarks, you can cut through the noise of the crowded London market and find a genuine growth partner.

If you're going through this process and want a second opinion, or want to see how a specialist B2B paid ads consultancy would approach your business, we offer a completely free, no-obligation 20-minute strategy session. We can take a look at your current efforts, talk through your goals, and give you some actionable advice you can use, whether you decide to work with us or not.

Hope that helps!