The people who left your firm, your client and your competitor are now sitting inside twenty other companies carrying an accurate opinion of you into every one of them.

1. McKinsey built one of the most valuable networks in business by keeping in touch. Its alumni directory runs to tens of thousands of former consultants, deliberately maintained, and those alumni end up in senior positions where they hire the firm. It is not sentimentality. It is the most efficient business development program in professional services.

2. Your client’s departed employees are witnesses. Everybody who used your product or sat through your engagement now works somewhere else and gets asked, informally, whether you were any good. That conversation happens constantly, you are never present for it, and the answer was decided by how you behaved on the bad days.

3. A coaching tree outlasts a record. In football, the measure of a great coach is eventually how many head coaches came off his staff. The same is true of firms: the people who trained under you and went on to run things are a longer-lasting reputation than any single engagement.

4. Nobody maintains this deliberately, which is the opportunity. A spreadsheet of everyone who has worked with you, worked for you, or worked at a client, with where they are now. Twenty minutes a quarter to maintain. Almost no small firm has one, and every large one that does swears by it.

5. Send something, twice a year, that is not a sales email. The recurring thing you publish is perfect for this: it arrives, it is useful, it requires no response, and it keeps you resident in the memory of two hundred people who already know what you can do.

6. Boomerangs are the best hire and the best client. Someone returning knows the standards, needs no onboarding and chose you a second time with full information. The same is true of a former colleague who becomes a buyer – they have already run their diligence, years ago, in person.

7. Treat the exit properly, because that is when this is decided. How you handle a departure, an offboarding or the end of an engagement determines every future conversation about you. It is the cheapest reputation work available and it happens at precisely the moment everybody is least inclined to bother.

8. Introduce them to each other. The network only becomes an asset when the members find it useful independently of you. Two introductions a month and you become the connective tissue of your own alumni group, which is a permanent position nobody can take.

9. This is the outward-facing half of the advocacy problem. Everybody writes about employee advocacy meaning current staff posting on social media, which is dead in practice. The version that works is about people who have already left, which is why it stays unclaimed.

The bottom line. Fifteen buyers said advocacy is obvious in theory and dead in practice. It is dead because everybody aims it at the people still on payroll, who are being asked to do marketing as a favor. The alumni are not doing you a favor. They are just answering a question honestly, and you decided the answer years ago.