The Narrow Base: A Concentration Audit for UK Client Portfolios

A full order book is often treated in UK professional services as proof of health. It is a pleasant condition, but it is not the same as resilience. A practice can be busy every day and still be exposed if two clients account for most of its revenue. The risk is not theoretical: one delayed programme, one change of sponsor, or one procurement review can remove a large share of forecast income before a replacement has been qualified.

In the current market, where UK buyers are cautious about committing budgets and many consultancies are carrying lean benches, concentration deserves a formal test rather than a vague sense of comfort. The purpose is not to reject large clients. It is to know what the business would look like if one of them paused.

Why a full diary can mislead

Busy delivery creates its own evidence. Invoices are issued, utilisation looks strong, and the sales conversation feels less urgent. That is precisely when concentration can deepen. The largest client receives more attention because it generates more work; smaller clients receive less because there is no immediate capacity. Over time, the practice becomes better at serving one kind of buyer and less practised at finding others.

The warning signs are rarely dramatic. A monthly retainer becomes a weekly commitment. A single department becomes the whole account. A sponsor who once asked for a proposal now asks for a favour. None of these events is misconduct. Together they describe a relationship that has become too important to the supplier's cash flow.

A simple concentration test

A useful test should be quick enough to repeat and blunt enough to prompt action. Start with a rolling twelve-month view of invoiced revenue and a forward view of contracted or confidently forecast revenue for the next two quarters. List every client and calculate its share of each total. Then apply three practical checks.

First, identify any client above 25 per cent of revenue. A client at that level is significant but not automatically dangerous. Second, identify whether the top two clients together exceed 50 per cent. If they do, the practice has a concentration event, even if both are excellent clients. Third, check the same principle for decision-makers and referral sources. Two sponsors inside one large organisation can look like diversity on a client list while behaving like a single point of failure.

The thresholds are not law. They are prompts. A specialist practice may reasonably accept higher concentration for a defined period, provided it has cash reserves, a clear exit date, and a live alternative pipeline. What matters is that the decision is explicit.

How dependency distorts the relationship

Concentration affects more than finance. It changes the texture of client conversations. When one client pays most of the bills, scope discussions become harder. A request that should be treated as a change is absorbed as goodwill. A deadline that should be challenged is accepted because the relationship feels too valuable to disturb. Pricing follows the same pattern: renewals are kept flat to avoid a difficult conversation, even when the work has grown.

The most serious distortion is the willingness to disagree. Good client work depends on honest friction: pointing out a flawed assumption, declining a rushed start, or explaining why a requested report will not answer the board's question. A supplier with a narrow base may still offer those views, but the commercial incentive runs the other way. The client may never notice. The supplier feels the strain in delivery, margin, and morale.

This is not an argument for treating large clients with suspicion. It is an argument for designing the relationship so that sound judgement remains affordable.

Widening the base without turning down good work

The answer is rarely to refuse profitable work. It is to change the conditions under which it is accepted. A practical plan has four parts.

The first is capacity discipline. Reserve a small proportion of delivery capacity for new or smaller clients. Even two days a month can keep a practice in contact with buyers outside its dominant account. The reserve should be protected in the same way as a client deadline, not treated as spare time.

The second is a modest pipeline habit. Instead of a large business development target, set a small number of qualified conversations each month. One useful introduction, one follow-up with a former client, and one written approach to a relevant buyer may be enough to keep alternatives warm. The aim is optionality, not a second full-time sales effort.

The third is to use the largest client deliberately. Ask for introductions to adjacent departments, not simply more work from the same team. If the client values the practice, that goodwill is an asset. It should be converted into a wider relationship before the current sponsor moves on.

The fourth is to review terms at natural boundaries. New pricing, clearer scope definitions, and agreed review points are easier to discuss at renewal than in the middle of a delivery crisis. A concentration clause is not necessary; a calendar reminder is.

A quarterly discipline

Concentration should be reviewed quarterly alongside cash flow and delivery. A simple page is sufficient: revenue by client, forecast by client, top-two share, largest decision-maker, and the status of two named alternatives. If the top two exceed 50 per cent, the review should ask what would happen if either paused for ninety days. If the answer is that the practice would need to make immediate redundancies or borrow, the risk is already material.

A healthy order book is worth having. A narrow base is not. The test takes an hour; the consequences of skipping it can take much longer.