Peter is credited with creating a significant part of the tight, driving sound that was the Oils, described as being an aggressive bass guitarist. He played on many of the band's most popular albums, including Place without a Postcard (1981), 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 (1982), Red Sails In The Sunset (1984) and Diesel and Dust (1987), as well the band's two studio EPs, Bird Noises (1980) and Species Deceases (1985).
He is credited with the bass lines of some of the band's most popular songs, including "Only the Strong", "US Forces", "Power and the Passion", "Best of Both Worlds", "When the Generals Talk", "Progress", "The Dead Heart", "Put Down That Weapon", "Dreamworld" and "Beds Are Burning".
Gifford joined the band in 1980 after hearing on the radio about the auditions for a replacement bass guitar player for Andrew 'Bear' James. He was actually driving over the Sydney Harbour Bridge to work as a roadie at the time. Andrew James was quite ill by this time and he had to withdraw from the band. The band was looking for a much more aggressive style of bass playing (an 'animal' as described by guitarist Jim Moginie) and Gifford fitted perfectly.
Gifford predominantly played a Fender Precision bass guitar and this can be seen in the 'Oils On The Water' Goat Island (Sydney, Australia) concert in 1985. His bass solo work in live performances of "Stand in Line" was his signature, so much so that the only reason why the 'Oils wouldn't play this song later on is because replacement bass player Bones Hillman couldn't play the bass line. Other songs featuring great bass line by Gifford include "No Time for Games", "Don't Wanna be the One", "Written in the Heart", "Lucky Country", "Power and the Passion", "'Somebody's Trying to Tell Me Something" as well as the songs from the Species Deceases EP. He also played the Chapman Stick on the tracks 'Sleep' and 'Who Can Stand in the Way' on the Red Sails in the Sunset album and in concert.
Gifford contributed significantly to backing vocals for the band, and is credited by long time producer Nick Launay as being a significant contributor in the recording studio.
In Australia, the Oils were most popular and successful in the 1980s and the sound Gifford brought to the band was an important part of that.
After leaving the band, he started Wicked Weasel, a direct marketing business specialising in micro bikinis. The company has built an international reputation for female swimwear and underwear.