As a deal, it is every marketing man's dream. In a single negotiation a UK consultancy can transform itself overnight into an enormous international player with offices across the world.

As part of the deal, struck with two or three like-minded foreign firms, you gain access to a wide range of prestigious overseas clients, as well as having the opportunity to grow your UK business on the back of an endless supply of leads from your new friends. What's more, it's cheap. The set-up costs are low, a profit share on certain contracts can be negotiated, the motivational benefits to your staff are huge and the value of your new access to specific market knowledge and expertise cannot be overstated.

But although the benefits of such a lucrative negotiation may immediately revolutionise your business in a stroke, the downside appears when you look at the longevity of the relationship and the work required to maintain it. "Your partner might be sharing your name but it doesn't necessarily mean it's sharing your working practices," warns Tim Wray, chairman of Turner & Townsend, tellingly. And who's to say that while you're desperately trying to develop a new synergy strategy to assess further business opportunities, your partner isn't already courting your largest clients with a view to disappearing into the sunset with key contracts?

As in any relationship, the key issue is trust. And although this trust seemed to have broken down in the relationship between Gardiner & Theobald and its international partners Levitt & Bailey and Ryder Hunt in the alliance it signed nearly 10 years ago,it has still given G&T an invaluable insight into the workings of complex international market. In the meantime, it has moved on: it is now a member of the select league of alliance-free international consultancies such as Gleeds and EC Harris, which have opted for the expensive but safer alternative of growth by acquisition.

But that's not to say global alliances do not work for the right firms in the right countries. Bucknall Austin looks set to make the leap and sees value in the international relationship left vacant by G&T. And you only have to look at the different models of Davis Langdon and Cyril Sweett, which is looking to operate in partnership with foreign firms in emerging nations such as India, but with set criteria for the governance of the relationship. "You need very strong territorial rules and you've got to stick with them," insists Francis Ives, Cyril Sweett's chairman.

And for those firms committed to the complex business of managing global alliances, the relationships are seen as critical to the success of the business. Client care and your product ideally need to be standardised across the partner firms, alongside certain business systems, such as IT. As one senior QS puts it: "A global alliance exposes you to the world and you must understand that your reputation depends upon it. So if you're going to be serious about the relationship, you have to spend time and effort with your partner to make it work." And who can argue with that?