Join Edith Bowman and Colin Murray at the Stranraer Oyster Festival, as celebrations mark the start of the native oyster season. They sail into Loch Ryan to Scotland's largest oyster bed to discover why they're so special. Chef Julie Lin discovers bargains in the World Food aisles, and gets the low down on low fat, semi-skimmed and full fat milk. Farmer Jim Smith gets stuck into some sticky sweets.