hey Brightenrosie,
I think slickers thinks you mean a pastry type chicken and mushroom pie, as anything with pastry i.e. savoury pies etc don't qualify for any free food allowance, so it would be 1 syn for every 20 calories.
However I presume this is a potato topped pie, in which case it WILL qualify for a free food allowance and you can't use the 1 syn for every 20 calories rule??
Is it this one?:
Be Good to Yourself, Chicken & Mushroom Pie, Potato Topped, chilled, 450g pack
If so it is 9 syns on Original or Extra Easy for 450g
or 10.5 syns on Green for 450g
info taken off syns online