Leslie Perrin is managing partner of Osborne Clarke. He can be contacted at leslie.perrin@osborneclarke.com.

This week a letter arrived at the office that sent a palpable wave of despair through our marketing team. The letter was from a directory – a big two directory – advising us to start preparing our submission for the new edition.

You can understand their gloom. For law firm marketing teams, the directory season is now the legal equivalent of groundhog day – something they're forced to relive day after day after day. In fact, the worst thing about directories is the grim realisation that, as with football and soft fruits, there is no longer a season.

Little wonder then that the recent, interesting report on directories by Wheeler Associates has been so eagerly seized upon by managers and marketers (and the media that predigest their food for them). This, after all, is a report that put its money where few of us would put our mouths. It dares to suggest that directories are about as useful as a British beef banger in a boucherie.

Marketing departments will have greeted this news with something approaching rapture, especially in the largest City firms which are still nostalgic for the days when clients had no knowledge or power. These firms seem, strangely enough, to be among those who commissioned the report in the first place. Naturally the directories are busy wheeling out their statistical quarrels with this premise but, frankly, their arguments don't do them any favours. So let's give them some that do.

The fact is – and I hope the magic circle marketers are sitting down – directories have done law firms, their people and their clients an enormous service. Perhaps, their great contribution – and by 'they' I mean the big two – is to have forced a notoriously secretive and lazy sector to take a long hard look at itself in the mirror. Like some editorial Richard and Judy, they've made us over and shaped us up, except they made us do the work ourselves.

At the very least, they've given firms the opportunity to think about, and make statements about, what makes them unique – and the cause of specialisation has been much nourished in the process. Firms focusing on particular sectors have used the directories to feed their aspirations. That process has in turn forced up standards of client care and dragged value to the heart of what we do.

And do lawyers take this seriously? You only have to watch the swinging dicks of magic circle corporate law firms at the launch parties of the big two directories as they tear open the new book with trembling fingers. You betcha they do.

Despite the unquestionable power that they wield, the duopoly of the big two has been a good thing. Basically, we're in symbiosis territory, this is a mutually beneficial relationship. They need us, certainly, but we need them as well – not an escalating number of them – and not simply for the reasons they would have us think. Sure, their influence is difficult to evaluate. But so is professional services marketing per se. With the emphasis on reputation management and client care, we know that the factors that persuade clients, or lawyers, to stay put or move on are both subtle and complex. All I know is, the harder we work, the luckier we get.

As for the rest the legal listings, the no-value catalogues – they might well think it's all over. If this report is anything to go by, it is now.