Oxford Cheese Company
A really nice cheese shop in the Covered Market (on the Market Street side), which specializes in farmhouse cheeses.
I recommend the Marksbury Cheddar, and the Oxford Isis is creamy, tangy, and very smelly!
The Spitfire is a lovely chili cheese - perfect for toasties, in burgers or just on a cracker.
He sells Oxford Blue made in a factory in Derbyshire though.