Cornish pasties are Cornish Pasties - not in Devon, Northumberland, Bedforshire or Dorset....they have been protected as is Champagne, Melton Mowbray Pies or Stilton....
Bedfordshire does something akin to an old pasty, half meat and half fruit inside a pastry oblong. Dorset ones are an abortion as they use mince (ye-uck). As OG says, use quality chuck, potato, swede, onions and seasoning and learn to crimp the pastry, then you are away.
For example - how can this mess be a Cornish Pasty? It's crimped wrong, has mince in it, as well as peas and carrots. Yeah Gads. I'm surprised that they haven't been done yet for the misnomer.
http://www.greggs.co.uk/menu/savoury/pasties-and-bakes/cornish-pasty/