butler and his musical partner david mcalmont, along with a number of other musicians, formed the backbone of duffy's band for her debut album, "rockferry", which was released on a&m records on 3 march 2008. the black-and-white album art and video for the title track were shot by directors luke seomore and joseph bull, on and around the ffestiniog railway in porthmadog, which was renamed 'rockferry' for the occasion. according to duffy, "the album took nearly four years to make. we had to hire cheap, tiny studios and sometimes there would be three-week periods between writing and recording." bernard butler, who was not initially paid, produced four songs for the album, including the single "rockferry". the singles "mercy" and "stepping stone" were co-written and produced by steve booker, and the second single "warwick avenue", by jimmy hogarth and eg white. duffy released the debut limited-edition single "rockferry" in november 2007; it was followed by "mercy", produced and co-written by steve booker, which went straight to number one. "mercy" was the last song written for the album. the single was physically released on 25 february 2008. she revealed that both "mercy" and "stepping stone" are autobiographical; "mercy" is about "sexual liberty" and "not doing something somebody else wants you to do", and "stepping stone" is about not expressing her feelings to a person she fell in love with. "warwick avenue" was the second single released from the album. the song occurred when duffy, then 19 years old, was familiarising herself with the london underground and accidentally found herself at the warwick avenue station. the following day the song "just sort of came out". at first the video for the song was meant to be an elaborate production, but ended up a tearful head shot in a taxi cab with duffy's mascara smudging. duffy has said "that's as close as i'm ever going to get to doing a performance that's real in a video."