Family fish pie

I’ve eaten a lot of fish pie in my life (what mum and grandmother hasn’t?) but I still think this one is the best for flavour, for freezing and for popularity with everyone. I first learnt how to make it at cooking school fifty-six years ago! This method uses 50% cornflour and 50% plain flour to thicken the sauce, which is perfect for freezing. Plain flour gives the sauce a better texture but doesn’t defrost as well.