Social media marketing in London: what an agency can own, what it can only coach, and how to label the paid work

Social media work divides into two things: what an agency can do for you, and what an agency can only do with you. Consumer brands buying reach are mostly buying the first. Professional firms buying credibility are mostly buying the second, and a retainer written as though those were the same purchase is the commonest way a London social budget disappears. So decide which one you are buying, pick platforms from the business rather than from whatever is growing, write down what the agency produces and what it has to extract from your own people, and label paid and gifted work the way the CAP Code requires.

Two buyers, two different purchases

London's social media market splits more sharply than most. On one side are consumer brands, retail, hospitality, food and drink, fitness and events, who want attention at volume. On the other are law firms, accountants, consultancies, asset managers, insurers, recruiters and enterprise software businesses, who want a small number of named people to find them plausible. The work looks similar on a calendar and is almost nothing alike underneath.

	Buying reach	Buying credibility
What is produced	Short video, stills, offers, user content, paid creative at volume	Explanations, points of view, commentary on things that just changed
Who appears	Staff, customers, creators, models	The partner, the founder, the specialist. Nobody can stand in for them
Where it runs	Instagram, TikTok, YouTube, Facebook, plus paid distribution	Mostly LinkedIn, mostly from a named person's account
What counts as working	Reach at an acceptable cost, saves, shares, repeat purchase	The right accounts reached, inbound enquiries, invitations, applications

Pick the platform from the business

In the United Kingdom, anything sold to a committee is largely a LinkedIn question, and the account that does the work is usually a named person's rather than the company page. Company pages carry the announcements; people carry the opinions, and opinions are what get read and forwarded. If your buyer is a general counsel, a finance director or a procurement lead, that is where the hours go.

Consumer categories are not a LinkedIn question at all. Short video on Instagram and TikTok does the discovery, YouTube does the long explanation and holds its value for years, and Facebook still matters more than London marketers tend to admit, particularly for local trades, older audiences and groups. Pinterest earns its place in interiors, weddings, food and anything visual with a long planning cycle. Everything else varies so sharply by category that the honest answer is to look at where your last twenty customers actually spend time and start there.

The ownership boundary, written into the contract

This is the clause most London retainers leave out, and it is the one that decides whether the work happens.

• An agency can own: the calendar, editing and design, paid distribution and its targeting, community management inside rules you agree, the asset library, the reporting, and the discipline of shipping on the days it said it would.
• An agency can only coach: the partner recording a two minute answer to a client question, the founder's actual view on something contested, the engineer explaining why the cheap version fails. Nobody can produce those on your behalf.
• So buy the coaching explicitly. Name the people, name the commitment, put the recording slot in their diary as a recurring appointment, and make a missed slot visible in the monthly report. A retainer that assumes goodwill will produce six good weeks and then a quiet drift into stock posts.

Disclosure, and the rules the ASA actually enforces

Advertising in the United Kingdom has to be obviously identifiable as advertising. That duty sits in the CAP Code, which the Advertising Standards Authority enforces, with consumer protection enforcement from the Competition and Markets Authority alongside it. In practice it means several specific things for social work.

• If you pay a creator, gift them a product, or give them anything of value in return for a post, that post is an advert and has to say so up front, where a reader sees it before they read the content, not in a cluster of hashtags at the end.
• The same applies to affiliate links, to competition entries that require a purchase, and to your own staff posting about the company in a way a reasonable reader would take as independent.
• A paid partnership cannot be presented as a personal recommendation that just happened. The relationship has to be clear from the post itself.
• Any performance, comparison or health claim needs evidence you hold before the post goes out, and testimonials have to be genuine and attributable.
• Financial services, health, gambling, alcohol and anything aimed at children carry extra restrictions, and in financial services a promotion has to be signed off before publication by somebody with the authority to do it.

The ASA publishes the names of online advertisers who do not put things right, which is a reputational problem rather than a fine, and in professional services a reputational problem is the whole risk. Agree the labelling convention with your agency on day one and have it in the brief for every creator.

Where social meets your database

A lead form on a social platform collects personal data, so UK GDPR applies to it: a lawful basis, a privacy notice that says what you will do, and a record of consent where consent is what you relied on. Marketing email to consumers runs under PECR, which means consent unless the narrow existing customer route genuinely applies, with an easy way to stop in every message. Custom audiences built from your own customer list need a basis too, and a privacy notice that admits you do it. Keep the records with the list rather than in somebody's inbox.

Reach work and credibility work need different numbers

Judge a reach programme on paid efficiency, saves and shares rather than likes, repeat purchase, and whether the content library is getting cheaper to produce per usable asset. Judge a credibility programme on whether the named accounts you want have seen the work, on enquiries that mention something you published, on speaking and panel invitations, on recruitment applications, and on whether the partner's connections now contain the people who sign contracts. Follower count tells you almost nothing about the second one, and measuring it there is how a good programme gets cancelled.

Questions that decide a London social media brief

Do we need a London agency, or can this be done remotely?

Strategy, editing, paid distribution and reporting travel fine. Filming does not. If your plan needs regular footage of your own people, somebody has to be in the room with a camera, and that is the part worth hiring locally.

How many posts a month is the right number?

The number your production can sustain at a quality you are happy to be judged on. Work out what one good piece costs you in time and money, decide how many of those you can fund every month for a year, and commit to that. A cadence you keep beats a bigger plan you abandon in March.

Should partners post from their own accounts or the company page?

Both, for different jobs. Named accounts carry the point of view and get the reach. The company page carries announcements, roles, client news and the things a stranger checks before a first meeting. Give the partners a clear line on what is theirs to say and what needs a second pair of eyes.

Do we have to label a gifted product post?

Yes. If value changed hands and you had any control over the content, it is an advert and the label goes at the start. Put that in the creator contract along with the approval step, so neither side is improvising.

If we change agency, what should come with us?

Everything, and the contract should say so before you sign it. The platform accounts and the business manager should sit under your own limited company, with the agency holding access it can lose. The agreement should assign copyright in the work to you, and the handover should include the source files, the raw footage and the image licences.

What an assistant says about your category, and where it got it

A buyer who wants a social media agency in London increasingly asks an assistant before they ask a colleague, and the same thing is true of their buyers asking about them. Those answers are drawn from third party pages, trade coverage and directories, not from the feed you spent the year filling, so a firm can be the most visible account in its category on LinkedIn and still go unnamed when somebody poses the question in plain words. Checking what comes back, and which pages produced it, tells you whether your reputation has reached the places these systems read at all. AI Knows Us puts the question to each assistant in a buyer's own words and names the pages the reply leaned on.