Drayton Bird, Steve Harrison, Randy Haunfelder, Jeremy Bullmore, Steve Henry, Gerry Moira and John Steel. (I would mention more women, but since I look ten years older than I really am, they probably would not thank me for it).
Now this seems quite a startling example of the Pareto principle: if you gain 70 per cent of what you learn from perhaps 4 per cent of the people, patently older people have a value that goes far beyond what they bring to their individual work.
Why don't we appreciate this more? And keep more people after 40, even as they get a bit pricier?
Essentially, there is a very simple explanation. Payment by the hour. This encourages you to reward people not in proportion to how valuable they are, but how saleable they are to a client. Since a client with a job does not see any immediate benefit from the wider contribution of wiser heads to the culture of the agency, he won't pay for it. This eroded an old group-heads system, which helped knowledge trickle down from one generation to the next.
The single best ingredient to a successful pitch is a 50:50 mix of age groups. The kind of mix of experience and enthusiasm that is often unacceptable to the client's procurement department once you win the business.