Stuart - I hesitated before responding as the timing of your question would look like a stitch up given what I'm about to say...
We organise for sales trainers to run "<a href=http://events.top-consultant.com/UK/careerconference.aspx?ID=423>The Art of Selling Consulting Services</a>" a couple of times each year and the next session is on 25th June (follow the link for details). It's far and away our most popular event and the feedback from past delegates you'll see is compelling.
Post here if you need any more info than is provided via the above page.
Rgds, Tony Restell