Fairy is a brand of washing-up liquid produced by Procter & Gamble at their West Thurrock factory (The London Plant), England. Fairy liquid is traditionally green, prompting the well-known advertising jingle “Now hands that do dishes can feel soft as your face, with mild green Fairy Liquid”.
As of 2008, Fairy is sold in most parts of Europe, although regional names vary. Fairy liquid is available in a variety of colour and scent combinations. The iconic white bottle with red cap was replaced with PET bottles.
In the UK, Fairy Liquid has become a genericized trademark for washing up liquid.
Info gleaned from Wikipedia