One Contract, One Fate: How UK Firms Measure and Reduce Client Concentration

There is a particular kind of conversation that recurs in growing UK businesses. The accounts look strong, the order book is full, the bank is comfortable, and yet the managing director cannot say what the business would look like in eighteen months if one relationship ended. That is not a sales problem. It is a governance problem, and it tends to appear at exactly the point when the firm has least appetite to address it.

What concentration actually costs

The obvious exposure is revenue. The less obvious exposures are usually more damaging.

A customer that represents a large share of turnover acquires pricing power by default, whether or not it chooses to use it. Annual price reviews become one-sided. Requests for extended payment terms, additional stock holding or unpaid scope become difficult to refuse, because the alternative is a hole in the plan. Lenders and credit insurers read the same accounts and apply their own concentration tests, often capping facilities or raising margins. Key staff attached to the account become a retention risk in their own right. The firm retains the legal structure of independence while losing much of its practical freedom.

Measuring concentration honestly

Most firms measure the wrong thing. Revenue share is the headline figure, but it flatters. A customer representing forty per cent of sales and fifteen per cent of gross profit is a different proposition from one representing thirty per cent of sales and half the profit.

A useful quarterly assessment covers at least the following:

• Share of revenue and share of gross profit for the largest client, and for the top three combined.
• Share of receivables — a single debtor can dominate working capital as well as income.
• Share of capacity, measured in whatever the business actually sells: machine hours, dedicated staff, account management time, warehouse space.
• Contract tenure and notice position — the renewal date, the notice period, and whether termination can occur without cause.
• Sectoral concentration, since three customers in one sector can behave as a single exposure during a downturn.
• Tendered or renegotiable revenue — the proportion of income that will be competitively retested within the next twenty-four months.

As a rough framework, a single client above a quarter of gross profit deserves standing board attention. Above forty per cent, a written plan should exist. Above sixty per cent, the business is effectively a division of its customer, and the strategy should say so plainly rather than avoid the description.

Reading the contract as a risk document

Commercial terms are usually negotiated by the party with the most leverage, which is rarely the smaller supplier. Even so, several clauses are worth contesting, and a surprising number can be improved simply by asking before signature rather than after.

Notice and term. A three-year term with ninety days' notice for convenience offers less security than it appears. Seek symmetry, or a longer notice period after the first year.

Price review. Indexation linked to a published measure, applied annually, protects margin without an annual argument. A fixed price for three years transfers inflation risk entirely to the supplier.

Volume commitment. Where none exists, the supplier carries all demand risk. Where one exists, check whether it is binding and what happens if it is missed.

Change control. Scope creep is concentration's quiet accomplice. A written process with priced variations protects both margin and relationship.

Payment terms and set-off. Long terms combined with broad set-off rights allow a large buyer to withhold payment across several invoices at once.

Exclusivity. Restrictive exclusivity can foreclose the very diversification the business needs. Resist it, or bound it tightly by sector and geography.

Liability caps and insurance requirements. These should be proportionate and matched to cover actually held.

Exit assistance. If the contract ends, what transitional support is owed, and is it paid for?

Diversifying without destabilising

The instinctive response — chase new business hard — is often the wrong first move. Service levels on the core account slip, the anchor client notices, and the firm creates the very event it feared.

A more measured sequence works better. Protect the core account first, and treat its service metrics as non-negotiable throughout. Then set a target and a glide path: for example, reduce the largest client from fifty-five to thirty-five per cent of gross profit over twenty-four months while holding absolute revenue steady. That framing makes clear that growth, not contraction, is the mechanism.

From there, three routes tend to work. Adjacent sectors are usually the cheapest to enter, since the capability already exists and only the buyer changes. A productised, standard-priced offering aimed at smaller customers builds volume without competing for the same account management resource. And additional sales capacity, recruited before it is needed, gives the pipeline time to mature. One caution is worth stating: new business won at marginal prices does not constitute diversification. It swaps one fragility for another.

A case in point

A North West specialist packaging converter, whose name we have withheld, arrived at a familiar position. A single grocery retailer accounted for sixty-eight per cent of revenue and an even larger share of profit. The relationship was good, the terms were not: three-year fixed pricing, ninety days' payment, twelve months' exclusivity across the grocery channel, and no volume commitment.

Over twenty months the firm took four steps. It renegotiated, conceding firmer service-level commitments in exchange for annual indexation, a shorter notice period and a narrowing of exclusivity to a defined product category. It recruited one business development lead with a brief confined to non-grocery sectors. It developed a short-run service aimed at pharmaceutical and e-commerce fulfilment customers, priced from a published rate card. Finally, it ran a stress test modelling the loss of the anchor client on ninety days' notice, which revealed a cash gap the board had not previously quantified and prompted a modest facility increase.

At the end of the period, the largest client represented forty-one per cent of revenue, absolute revenue had risen by roughly a fifth, and the account remained intact. The headline number had fallen because the business had grown around it.

Governing the exposure

The work is only durable if it is reported. A single concentration metric should sit in the quarterly board pack alongside the renewal calendar and the status of the diversification plan. The stress test should be refreshed annually, with the cash bridge — not merely the revenue loss — set out explicitly. If the answer to the question in the opening paragraph is still unknown, the plan is not yet finished.