There is a lack of strong SEM professionals in the UK. There is a shortage of good PPC people and an even worse shortage of good SEO people. Gosh. If you're looking for someone savvy on both fronts then you are in for a search (oh, there's a touch of irony in there).
Imagine the scenario. You're a brand who lives or dies online. It might be that PPC is especially important to you. It may be that you've grown to the point where you do run the occasional TV campaign or direct marketing push but it is still largely Google who delivers you traffic.
You need to recruit. You may be after a Head of Search or some senior PPC or SEO role. You bring in the head-hunters. What will the head-hunters do?
The chances are high that the head-hunters will start to ring around the large and well known SEM agencies. These are the same agencies who might manage your rivals PPC or SEO campaigns. If head-hunters have the exclusive rights to your vacancy then they won't be shy in dropping your name in an attempt to lure in senior agency staff.
The attempt is likely to have unwelcome side-effects for you, though. Your head-hunters have just told the people tasked with matching and beating your online strategy that you are missing a key member of staff, are about to loose a key member of staff or are about to bring in a significant new member of staff.
Simple things like bidding technologies get reviewed when a new Head of Search arrives. If I discover that Brand X is looking for a new Head of Search then I'll put Brand X's search campaign on watch (if it's not on watch already). Let's see if they change from Atlas to Doubleclick, for example. That'll mean their AdWord campaign is likely to have to regain its history. Let's expect the new guy to try and make a strong start so let's watch out for new microsites, a new organic strategy or a review of affiliate networks.
Of course, all this applies to any other industry. If Brand X hires a new advertising agency then you know a new style of advert is likely. Old imagery, catchphrases or jingles may go. However, I argue the effect is even more extreme in the world of search. Why? There are fewer players and so head-hunters are much more likely to let the cat out of the bag and approach someone tasked to go against you. Tracking, bidding, linking, building, affiliations and copywriting are all externally measurable.
There are people out there watching you.