The Engine Is A Series Of Hoses
So after melting the power steering hose and getting a replacement made up (see below), as I was bleeding the system, there was a waft of smoke coming from the extractors. Having just fiddled with things around that area I stopped the engine and had a look. What I found was that the breather hose had been sitting against the exhaust manifold in two points and had melted through insulation and a large part of the hose.
So went and bought some longer hose, in order to re-route the hose as I did the power steering. After some effort to route it neatly (I had to take apart most of the intercooler and turbo piping) I did a final check to make sure nothing else was touching the exhaust. So hopefully now my ‘melting through direct contact with the exhaust’ problem should be solved.