.............I thought it was Sodexo too but I don't see their logo on the OS anymore. The deal will be as you say unless we took it back in-house.It was. Then ISS took over.
I haven't been to any modern stadia besides Wembley last time but I thought the catering there was good and not to dear. At least you could get served easy and get a seat to eat your food.
For now though ,we go to the Everton school and get a chip butty and a cuppa !