IDEO remains the grand name for a problem that has not yet learnt how to describe itself. Its best work begins with watching how people actually behave, then gives an unwieldy organisation something tangible around which to gather. The approach can feel elaborate for a small commission, and its vocabulary has been borrowed rather too freely by lesser firms. Yet when several departments must imagine a service together, few practices are better at turning uncertainty into a credible first move.

frog still carries the instincts of an industrial-design studio, even when the object in question is a service, an interface or a company itself. That heritage brings a welcome concern for how things are made, held and used, while its international scale supplies the researchers, engineers and strategists required by a complicated brief. It is the strongest choice when an ambitious idea must survive procurement, production and the realities of a large organisation without losing its shape.