Update;
310’s fitted to the front on Saturday, and alignment carried out (well, I was charged for it so they must have I guess). Won’t be returning to the place in Nailsea that carried it out. Didn’t mention the fact that they were unable to fit one of the wheel nuts, just left it in the car. Also, I had the wheels swapped over at the same time. Luckily I rememered to get the old ones just before driving off as they were still in the fitting area (no mention of ‘here are your old one’s mate’). Service was miserable too - probably the worst place I’ve been for tyres in the last 30 odd years. Anyway.....
Car was all over the place on the return trip home, so much so that I didn’t drive over 30 mph. Checked the tyre pressures, once I’d got back - 40psi FFS. I reduced that accordingly.
Car isn’t too bad around corners now (though not the positive feel I had before) I guess they may wear in a bit. But, I can’t keep it in a straight line on the motorway at 50mph, it’s all over the place and feels dangerous. Going to have to change the rears to 310s before I use it again and hope that will solve the issue.