The thing with STEM is that it will never become useless or unnecessary in a modern society that expects electricity at the flick of a switch, cures for all their diseases, fast intercontinental travel and instant entertainment from a flat-screen. Short sighted politicians may think that switching to a largely financial services based economy may be easy money, but in the long run it'll come back to bite us - in fact it already is.
Britain will be left behind the times if it doesn't increase the amount of STEM graduates and promote STEM careers. We'll be nothing more than a banking centre off the coast of France, full of people that have none of the vital skills in STEM that will advance our society, standard of living and energy efficiency. But meh, Britain chose consuming a long time ago, hence why we have so many marketing managers etc.; at least us STEM folks will still be useful in other countries, so long as we can learn a new language.