IMO it’s not that surprising: PPE is widely seen as the degree to do if you want to get into politics. So it’s not that people do PPE then find themselves drawn to the political world, it’s the reverse.

I studied politics and quickly realised there was a huge divide between those of us who wanted to study a broken system from the outside and those who coveted being one of the jeering bores in the House of Commons. Helped me lose whatever faith I had left in the political system.

and Eton first (or maybe one of a handful of * public schools)

( * not public as in the US sense but in the UK sense - yes it's backwards)