Many thanks to the BBC! They provide a wonderful list on this web page...
I'm finding their website very grown up but it is absolutely packed full of information!
Name: Polyethylene terephthalate
Known as: PET
Used in: Fizzy drink bottles and oven-ready meal trays.
Known as: HDPE
Name: Polyvinyl chloride
Known as: PVC
Used in: Food trays, cling film, bottles for squash, mineral water and shampoo
Name: Low density polyethylene
Known as: LDPE
Used in: Carrier bags and bin liners.
Known as: PP
Used in: Margarine tubs, microwaveable meal trays.
Known as: PS
Used in: Yoghurt pots, foam meat or fish trays, hamburger boxes and egg cartons, vending cups, plastic cutlery
This last category is used for all other plastics, such as melamine – often used in plastic cups and plates