Jezza, market knowledge is important, but the most important thing is being able to match the right person to the right job.
I am continually infuriated with the IT recruitment industry, many resourcers simply look for keywords without any understanding of the work. For instance, I have been routinely rejected for positions because I have not used the right keywords on my CV.
As an example, I work in Quality Management - even though a lot of this relates to software testing, some resourcers are unable to understand the correlation. Hence I have several CVs geared up for different 'keywords'.
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and they never return phone calls....