Calypso are doing an all-day oyster deal. It'll be 88rmb for 6 pieces of Fine de Claire #4 Oyster, 12 pieces for 158rmb, or upgrade with 2 glasses of selected white wine for 198rmb with 6 pieces and 398rmb with 12 pieces. You need to reserve a day in advance, and can do that by calling them on 2203 8889.