<Table> <Tr> <Td> "Rockferry" (2007) </Td> <Td> "Mercy" (2008) </Td> <Td> "Warwick Avenue" (2008) </Td> </Tr> </Table> <Tr> <Td> "Rockferry" (2007) </Td> <Td> "Mercy" (2008) </Td> <Td> "Warwick Avenue" (2008) </Td> </Tr> <P> "Mercy" is a song performed by Welsh singer Duffy, released as the second single from her debut studio album, Rockferry (2008). Co-written by Duffy and Steve Booker and produced by Booker, it was released worldwide in 2008 to critical acclaim and unprecedented chart success . As Duffy's first international release, the song is credited with firmly establishing her career and is now considered her signature song . "Mercy" received comparisons to Duffy's previous single, "Rockferry". Critical reviewers of "Mercy" noted similarities between the song to releases by Aretha Franklin, Dusty Springfield and The Supremes, as well as contemporaries such as fellow British singer Amy Winehouse . </P> <P> "Mercy" was nominated for several awards in 2008, including the Grammy Award for Best Female Pop Vocal Performance at the 51st Grammy Awards . Well received by the public, "Mercy" peaked at number one on the UK Singles Chart in February 2008, remaining atop the chart for five weeks, and went on to become the third - best - selling single of 2008 in the United Kingdom, with sales of over 500,000 copies in the UK that year . It achieved worldwide chart success, topping the charts in Austria, Germany, Greece, the Netherlands, Norway, Republic of Ireland, Switzerland and Turkey, and peaked within the top five of the charts in Belgium, Denmark, France, Italy, Japan, New Zealand, Romania, Spain and Sweden . Duffy attributed the chart success to the fact that "everyone is searching for liberty...from themselves or from the world they've created around them" and "everyone would like to be set free". It is Duffy's best - selling single to date . </P>

Who sings the song begging you for mercy