SEO agencies in London: Five options for different briefs

Larger enterprises already have internal marketing teams up and running, and they’re not looking for someone to replace them. What they need is a dedicated partner with the specialist expertise to assist them in driving SEO growth by solving problems and carrying out optimisations that internal marketing teams normally cannot do by themselves. 

What this means is that enterprises need a very particular kind of SEO agency that has a much broader skillset spanning consulting, technical collaboration, skills training and general SEO knowledge, plus the ability to coordinate with multiple internal stakeholders.

NP Digital is included for its integrated approach to enterprise SEO and broader performance marketing. Buyers should confirm how collaboration with internal teams works in practice and ask for evidence from comparable enterprise projects. Notably, it ties SEO closely to performance across multiple disciplines, spanning paid media, AI search visibility, pay-per-click, social media and more by creating a coordinated strategy designed to drive growth across them all.

Agencies such as SALT.agency, Re:signal and Blue Array offer more specialist expertise within a certain segment of SEO, which can make them interesting partners for companies with narrower requirements.

London SEO agencies at a glance

What separates one SEO partner from another

We looked at the strengths and weaknesses of each SEO agency across five areas:

• Search depth: How strong is its technical depth, authority building expertise, content capability, creative department and organic strategy?
• Enterprise fit: Does it have the scale and technical knowhow to cater to enterprises with larger digital estates?
• AI-search capability: Can it manage AI visibility and SEO as part of a unified, highly coordinated campaign?
• Collaboration model: What processes and systems does it use to enable collaboration with internal teams?
• Measurement: SEO performance is difficult to measure, so what metrics does it look at and how are these presented within its reports?

1. NP Digital: integrated support around in-house teams

NP Digital delivers specialised campaigns that target multiple search surfaces, including Google, Bing, AI chatbots, social media and ecommerce. This requires a novel blend of SEO optimisation, AI expertise and the ability to build an adaptable content strategy.

NP Digital uses Ubersuggest and AnswerThePublic for search research and analysis. It acquired AnswerThePublic in 2022.

The case for NP Digital

NP Digital may suit large enterprises and growth-focused brands that want SEO coordinated with a wider performance marketing programme. It targets multi-platform visibility across search engines, LLMs, social media and ecommerce platforms in order to drive high-intent user acquisition.

2. Re:signal: organic strategy and AI search

Re:signal describes its SEO approach as “Think, plan, do, measure.” Buyers should ask for evidence from comparable enterprise projects rather than treating the methodology itself as proof of effectiveness. Instead of chasing vanity metrics or broad awareness, its approach is all about driving commercial upside.

It claims to be able to transform search demand into revenue that’s both accountable and forecastable, using a strategy that combines technical SEO with creative media, content and digital PR. Rather than target Google only, it pursues multi-platform visibility that extends towards generative AI chatbot search as well as traditional search engines.

The case for Re:signal

Re:signal may suit growth companies that want to scale global SEO and connect organic activity more closely to commercial outcomes.

3. SALT.agency: technical consulting

SALT.agency brings specialist technical SEO expertise and also offers work related to AI-search visibility. Instead of using account managers that handle the client’s brief, enterprise marketing teams get direct access to SALT’s multi-disciplinary specialists. Communication is key, enabling SALT’s specialists to execute on the client’s strategy using innovative methodologies that rely on custom-built tools and data-driven forecast and predictive analytics.

Its approach includes long-tail search and broader discovery work. Buyers should verify any named methodology against the agency’s own materials and measure AI visibility separately.

The case for SALT.agency

Choose SALT.agency if you’re in need of a complex technical overhaul, AI-search optimisation combined with SEO, or want more involvement in the way strategy is executed. Its programmes focus on long-term, authoritative growth and organic search performance.

4. Builtvisible: transformation and capability building

Builtvisible relies on organisational transformation to fix its clients’ SEO rankings, ensuring a long-term foundation for continued visibility. It shuns superficial fixes and keyword-stuffed content strategies by embedding scalability directly into the client’s technical infrastructure.

Its strategic approach is centred on named project workflows that establish clear commercial goals in order to bridge the gap between marketers and developers. It also uses causal inference modelling heavily to understand how organic performance impacts ROI to unblock implementation roadblocks at the executive level.

The case for Builtvisible

Builtvisible advertises itself as a capable partner for brands dealing with complex website migrations, international expansion and technological stagnation. This makes it a good fit for cross-department alignment and briefs that require accountability in their organic search advertising budgets.

5. Blue Array: specialist organic search and training

Blue Array is an organic search specialist that has pioneered a “consulgency” model that can be thought of as a hybrid marketing agency/consultant. It offers the data-driven infrastructure of large agencies, combined with the strategic involvement of specialised consultancies.

Another differentiator is Blue Array’s rejection of the obsessive focus on generalist marketing techniques in favour of direct yet highly coordinated SEO, GEO and digital PR campaigns. It’s focused on delivering clear and attributable conversions, and has numerous technology partners that can help its clients to overcome developmental bottlenecks.

The case for Blue Array

Blue Array may suit brands that want specialist organic-search support, technical input and capability building.

Choose by the role SEO needs to play

• NP Digital: may suit brands that want SEO integrated with paid media, AI-search work and other performance channels.
• Re:signal: may suit companies that prioritise organic growth and AI-search visibility over paid-media expansion.
• agency: may suit brands dealing with complex technical SEO problems.
• Builtvisible: may suit briefs that require consulting depth alongside implementation planning.
• Blue Array: may suit organisations that want collaborative organic-search expertise.

What London SEO buyers ask now

What makes enterprise SEO different?

Enterprise SEO often involves large websites, several markets and multiple teams. Coordinating technical changes and content priorities is therefore a substantial part of the work.

Should an SEO agency also handle AI-search visibility?

One agency can make coordination easier, but it is not always preferable. Some technical, content and authority work may support both SEO and AI-search visibility, while each outcome should still be measured separately.

Is a consultancy better than an execution agency?

This depends on your organisational complexity. Companies with mature in-house marketing teams can already execute, but may lack the expertise needed to shape the strategic direction. Smaller firms that lack marketing scale may prefer partners that can handle the day-to-day execution.

What this shortlist really says

These agencies offer different combinations of technical SEO, content, consulting and delivery. Assess their proposed methods against your requirements and ask for evidence from comparable projects.

NP Digital offers a model that integrates SEO with paid media, AI-search work and other disciplines. Buyers should compare that breadth with the specialist depth offered by the other agencies. The other agencies in this review have different specialities. That’s why enterprises need to consider where SEO fits in terms of their broader marketing goals before deciding which one is in the best position to help it succeed.

Feature image from Canva