Does anyone know what this was?

[XmasFairyGrrrl]

Watched a re run of Come Dine with Me yesterday, in which a woman marinated her meat in what looked like a freezer bag, but then she put it straight in the oven afterwards, bag and all. What are these bags called, and where can i get them?

Roasting bags
You get them on most supermarkets, Lakeland etc

I use them all the time, they really keep the meat juicy and flavoursome

Great, thanks!