London has more digital agencies than any city in Europe, and most of their websites say the same things. This checklist is the one we would give a friend: what to look at, what to ask and what should make you walk away.
Start with the work, not the pitch
Ask to see three pieces of work for businesses like yours, and ask what each one produced. A good agency can show the work, name the result and tell you where it came from. A weak one shows awards, logos and percentages with no source.
Look for case studies that say what was measured and when. "Enquiries up 40 percent" means nothing without the period and the baseline. "4.6 Google rating across 341 reviews, captured 7 July 2026" is a fact you can check.
Meet the people who will do the work
- Who is the named lead on the account, and how many accounts do they run?
- Which work is done in-house and which is subcontracted?
- Is the person in the pitch the person in the monthly meeting?
Check the commercials
- Flat fees, not a percentage of your advertising spend.
- Accounts, analytics, domains and content in your name from day one.
- A minimum term with a reason behind it, and a notice period after it.
- Scope in writing before the first invoice.
Look at how they report
Ask for a sample monthly report. If it leads with impressions, followers and rankings, the agency is reporting activity. If it leads with enquiries, calls, sales and what changes next month, it is reporting outcomes. You want the second kind.
Warning signs
- Guaranteed rankings, guaranteed leads or guaranteed return on spend.
- A proposal that arrives before anyone has looked at your analytics.
- Prices that cannot be explained in terms of what is delivered.
- Testimonials with first names only and no company.
- A contract that renews automatically for another year.
A simple scoring method
Score each agency from one to five on four things: evidence of relevant work, the seniority of the people on your account, the fairness of the commercials and the quality of the reporting. Weight them equally. The agency with the best pitch rarely wins on this scoring, and the one that does is usually the right choice.
Questions people ask
Should we choose a specialist or a full-service agency?
If you need one thing done brilliantly, a specialist. If your channels need to work together and you do not want to manage five suppliers, a full-service agency with specialists inside it.
Does the agency need to be in London?
Not for most work. It helps for production days, workshops and sectors where being on site matters, such as hospitality.
How many agencies should we speak to?
Three is enough if you brief them the same way and ask the same questions.