Question: What was Phil Lynott's most successful group that included Brian Downey in four songs?

Context paragraphs:
Please Don't Leave Me (album): "Please Don't Leave Me" is a single released by John Sykes in 1982.  The song features Thin Lizzy band members Phil Lynott on vocals and bass, Brian Downey on drums and Darren Wharton on keyboards; Sykes would join Thin Lizzy as a permanent guitarist later in the year, replacing Snowy White.

Phil Lynott: Philip Parris "Phil" Lynott ( ; 20 August 1949 – 4 January 1986) was an Irish musician, singer and songwriter.  His most commercially successful group was Thin Lizzy, of which he was a founding member, the principal songwriter, lead vocalist and bassist.  He later also found success as a solo artist.

Back on the Streets (Gary Moore album): Back on the Streets is an album by Northern Irish blues-rock guitarist Gary Moore, released in 1978, and his first authentic solo record (1973's "Grinding Stone" album being credited to "The Gary Moore Band").  Thin Lizzy bassist/vocalist Phil Lynott and drummer Brian Downey appear on four songs, including "Don't Believe A Word" (which originally appeared on the 1976 Thin Lizzy album "Johnny the Fox") and the UK top 10 single "Parisienne Walkways".  On the album's sleeve, Moore is depicted leaving notorious prison Wormwood Scrubs in the Inner London Borough of Hammersmith and Fulham in a photograph by Chalkie Davies.

Brian Downey (drummer): Brian Michael Downey (born 27 January 1951) is an Irish drummer, best known as the drummer and a founding member of the rock band Thin Lizzy.  Along with Phil Lynott, Downey was the only constant member of the hard rock group until their break-up in 1983.  Downey also co-wrote several Thin Lizzy songs.  Allmusic critic Eduardo Rivadavia has argued that Downey is "certainly one of the most underrated [rock drummers] of his generation".

Sarah (Thin Lizzy song): "Sarah" is a pop song released in 1979 by Irish rock group Thin Lizzy, included on their album, "".  The song was written by the band's frontman Phil Lynott and guitarist Gary Moore about Lynott's newborn daughter.  The song was also issued as a single, and appeared on several compilation albums including "".  The song was never performed live by Thin Lizzy, but it was adopted as a live favourite by Lynott's post-Thin Lizzy project, Grand Slam, and featured on "Live in Sweden 1983", a recording of Lynott's solo band.

Thin Lizzy: Thin Lizzy are a hard rock band formed in Dublin, Ireland in 1969.  Two of the founding members, drummer Brian Downey and bass guitarist and lead vocalist Phil Lynott, met while still in school.  Lynott led the group throughout their recording career of twelve studio albums, writing most of the material.  Thin Lizzy's most successful songs, "Whiskey in the Jar" (a traditional Irish ballad), "Jailbreak" and "The Boys Are Back in Town", were all major international hits.  After Lynott's death in 1986, various incarnations of the band emerged over the years based initially around guitarists Scott Gorham and John Sykes, though Sykes left the band in 2009.  Gorham later continued with a new line-up including Downey.

Parisienne Walkways: "Parisienne Walkways" is a song by guitarist Gary Moore that reached number 8 in the UK Singles Chart in May 1979.  The song is featured on Moore's album "Back on the Streets" and features a vocal from Thin Lizzy frontman, Phil Lynott, who co-wrote the song with Moore.  Lynott also played bass guitar on the track, alongside Thin Lizzy drummer Brian Downey, thus reuniting the short-lived 1974 Thin Lizzy line-up which had recorded "Still in Love with You" and the single "Little Darling".  The melody of "Parisienne Walkways" is based on the jazz standard "Blue Bossa" by Kenny Dorham.  It was Gary Moore's signature song.

Dedication: The Very Best of Thin Lizzy: Dedication: The Very Best of Thin Lizzy is a compilation album released by rock group Thin Lizzy in 1991.  The only previously unreleased track was "Dedication", which was reconstructed after Phil Lynott's death using an old 8 track demo recording of the song (originally recorded around 1985) to provide the bass and vocal lines, with new guitar and drum parts added by Scott Gorham and Brian Downey.

Scott Gorham: Scott Gorham (born William Scott Gorham, March 17, 1951, Glendale, California) is an American guitarist and songwriter who rose to international recognition as one of the "twin lead guitarists" for the Irish rock band, Thin Lizzy.  Although not a founding member of Thin Lizzy, he served a continuous membership after passing an audition in 1974, joining the band at a time when the band's future was in doubt after the departures of original guitarist Eric Bell and his brief replacement Gary Moore.  Gorham remained with Thin Lizzy until the band's breakup in 1984.  He and guitarist Brian Robertson, both hired at the same time, marked the beginning of the band's most critically successful period, and together developed Thin Lizzy's twin lead guitar style while contributing dual backing vocals as well.  Gorham is the band member with the longest membership after founders Brian Downey (drummer) and frontman and bass guitarist, Phil Lynott.

One Night Only (Thin Lizzy album): One Night Only is a live album by rock band Thin Lizzy, released in 2000.  Thin Lizzy had reformed in 1996 for a series of gigs marking ten years since the death of singer/songwriter/bassist Phil Lynott.  Latterday Lizzy guitarist John Sykes now took the lead vocal while Marco Mendoza was recruited on bass.  The venture was popular enough to be repeated but by the time this album came out, original drummer Brian Downey had decided the affair was too disorganised and retired from the group leaving none of the original trio remaining.  Keyboardist Darren Wharton also quit around the time of this album's release.  The band, led by Sykes and Scott Gorham, subsequently continued performing with various lineups.  This album features ex-Ozzy, Whitesnake, and Black Oak Arkansas drummer Tommy Aldridge.

Supporting paragraphs: Back on the Streets (Gary Moore album) Phil Lynott
Answer: Thin Lizzy