Take the client at the top of your book, or the tenth, or the fortieth. Somewhere in the firm is a partner who could tell you what it took to win them. Almost no one could tell you what it would cost to lose them, and that is the number worth knowing.
What if you knew, for each of your top fifty, how long it had been since anyone spoke to them about anything other than the work in hand?
What if a client beginning to drift showed up while there was still time to do something about it, instead of in the fee figures a year later?
What if the ones who send you the most introductions got the attention their introductions deserve?
What if the question of what it would cost to lose them had an answer every partner agreed on?
How many of your top fifty would you call tomorrow if you knew they were being courted this week?
Clients are hard to win and expensive to court. The best ones took years: a referral that had to be earned, a first piece of work that had to go well, a partner who stayed close through two or three difficult moments. By the time a client is in your top fifty, they have seen the firm at its best and they know who to ring.
That is exactly why losing one hurts more than the fees suggest. The fees are the visible part. Underneath them is the work that client sends on without being asked, the introductions, the reference when a prospect checks you out, the partner's own standing. And the replacement cost: winning a new client of the same size takes more partner time than most firms would care to measure, at a worse rate of success, with none of the trust already in place.
I don't put a euro figure on it, because the figure is yours and you'll know it when you work it out. What I'd suggest instead is the quieter question: how long would it be before anyone noticed? In most firms the honest answer is about a year, because the first sign is a smaller invoice, and by then the client has had the conversation with someone else.
Here's how I take that off your plate
The first piece of work I do for most firms is a read of the book: the top fifty, read one at a time, with the quiet ones alongside. What comes back is short. For each account, what has changed on their side since you last worked together, who should call, the reason to call now, and a draft note for whoever owns the relationship. A one-page summary on top, walked through with the partners, ending with the calls to make in the next fortnight.
Then it keeps going. The accounts that matter most are watched, and when something changes on their side, a new appointment, a move, a sign that someone else is circling, the partner who owns it hears about it that week, with the note drafted. None of it needs the partners to remember to check.
Picture a firm with a client it has looked after for twelve years, whose finance director retired in the spring. The new one has never met your partner. The note that goes out in week one: "Congratulations on the role. We've worked with the company for a good while now, and I'd like to make sure what we set up for your predecessor still suits the way you want to run things. Would half an hour over the next few weeks be useful?" Short, warm, and sent before anyone else thought of it.
What one of them is worth is your number. Keeping them is my job.