Realised this morning that I had never actually checked the tyre pressures in the 9 months I have owned the car, as all the tyres looked 'normal'. But nothing is normal about this car, and that includes the tyre pressures. Unlike normal road cars that have tyre pressures around 28-32 psi, kit cars tend to have pressures of 19psi.
So I checked them at the local garage (today was such a glorious day I had to go for a run out) and they were:
Front Nearside: 19 psi (Good)
Front Offside: 13 psi (whoops)
Rear Nearside: 25 psi (A bit too high)
Rear Offside: 24 psi (Same)
So I dropped the rear tyres down to 19psi and topped up the Front Offside. Might be my imagination but seemed to handle a bit better and I didn't notice the squeal going around a left turn.
Better keep monitoring them from now on.