This little buttercup looking small flower is growing on a farm pond in Kent, England. The pond is very highly polluted and uncared for with sheep droppings in it and all around and is shallow depth yet this plant covers the majority of the pond - I could not work out if its roots went to the soil underneath or it just floated or both. The flowers reminded me of Caltha palustris but the leaves were of a different shape. Any ID appreciated! Regards Richard Masson