According to Spielmann's British Sculpture and Sculptors of Today (1901), it was Colton's breakthrough work:
After he had studied in Paris, Mr. Colton first drew notice to himself with the fountain erected in Hyde Park, executed to the order of H. M.'s First Commissioner of Works during a lucid artistic interval of the Government. The influence of Mr. Alfred Gilbert seems to be in this charming production; but it is open to the criticism that the figure is abruptly cut off at the middle.Indeed, it looks as though the girl is standing up wearing an enormous tutu.
Sadly, the artificial stone copy (made in the 1970s) has not worn well and, as an added indignity, the poor mermaid seems to have been renamed Little Nell for no readily apparent reason.
Where is the original?