Perfect for anyone looking for a date night in London's that's a bit different, this is one night your partner's not likely to forget in a hurry. Opium is one of London's true hidden gems, discretely tucked away behind an otherwise unassuming green door in the heart of bustling Chinatown. Have a a go in their arcade to find out which shots you've got a drink. Lunch Set Menu and 2 other offers. Hoxley and Porter 93 user reviews 4.