How can you measure the value of a consultant?

Consulting is an industry with a perennial value problem; because the work that consultants do can often be relatively abstract and strategic, it can be difficult to prove the value created by a given project. Is there anything that firms can do to help make their unique value-add more concrete in the eyes of clients?

Fiona Czerniawska; Edward Haigh; and Fergus Blair.

How can you measure the value of a consultant?
The Future of the Firm