This paper addresses three issues in the context of knowledge-intensive service (KIS) development, related to the competitive base of cities and the degree to which they possess distinctive sources of innovativeness. The first is, how may growing KIS, or consultancy, use influence client innovation? Although this is inherently difficult to demonstrate, the expertise and modes of operation of consultancies suggest that they do influence technical and organisational change amongst clients. The second issue is the segmentation of consultancy influence, especially by sector and types of firm. Finally, how far does the urban base of consultancy supply imply local, specifically urban, benefits for client innovation? Consultancy services are often delivered over wide areas from their urban bases, within national and international nexuses of corporate and public-sector service exchange. This question cannot be answered by focusing only on local exchange. Urban client-consultancy interaction needs to be set within a national and even an international context of specialist expertise exchange.