Simply that in a free market, the market would clear and sellers (talent) would reach an equilibrium with buyers (employers). That cannot happen because the buyers - for ingrained, cultural reasons of reinforcing a class hierarchy - refuse to play. So the most senior engineer in an organization, no matter how much value he creates, can never be paid more than a middle or in some cases junior manager incase he gets "ideas above his station" and fails to doff his cap to his "betters". That is the #1 problem in the UK employment market, the dead weight of the entrenched management class. Only in the finance industry does the talent market operate as it should, because contrary to popular belief, that's actually the only industry in the UK where the old boys network doesn't have a stranglehold.

If you're smart enough to be an engineer, you're smart enough to realize the only way to win is not to play. So you either go into finance, or leave the UK, or grit your teeth and accept that in order to do the work you enjoy, you're going to be poor compared to someone who couldn't do your job in a month of Sundays, but has the "right" connections.