Question: Legs & Co. was a dance troupe until 1981, replacing another called Ruby Flipper, on which BBC TV show?

Context paragraphs:
UST Yellow Jackets: The UST Yellow Jackets (or "UST YJ" or simply ""YJ"") is the official pep squad and drumline of the University of Santo Tomas.  It works together with the UST Salinggawi Dance Troupe, the official dance troupe of the university.  It is the official cheerdance team ("together with the UST Salinggawi Dance Troupe") of the University of Santo Tomas in the UAAP Cheerdance Competition.  The UST Yellow Jackets also perform for halftime during the games of the UST Growling Tigers, the university's Men's Basketball team in the University Athletic Association of the Philippines.

Hip Hop-eration: Hip Hop-eration is a New Zealand documentary film about a dance troupe managed by communications consultant turned flash mob choreographer Billie Jordan on Waiheke Island in New Zealand.  The dance troupe (called "Hip Op-eration"), with an average age of nearly 80 among its members, decided to apply for the special exhibition category in the Las Vegas Hip Hop International championships of August 2013.  The documentary documents their journey through time, space and doctor's visits.  It opened theatrically in Auckland on 22 September 2014.

Stuart Hodes: Stuart Hodes (born 1924) is an American dancer, choreographer, dance teacher, dance administrator and author.  He was Martha Graham’s partner, danced on Broadway, in TV, film, in recitals, and with his own troupe.  His choreography has appeared on the Boston Ballet, Dallas Ballet, Harkness Ballet, Joffrey Ballet, San Francisco Ballet and other troupes.  He taught at the Martha Graham School, Neighborhood Playhouse, NYC High School of Performing Arts, headed dance at NYU School of the Arts and Borough of Manhattan Community College.  He was Dance Associate for the NY State Council on the Arts, dance panelist for the National Endowment for the Arts, president of the National Association of Schools of Dance, and a member of the First American Dance Study Team to China in 1980, returning in 1992 to teach the Guangzhou modern dance troupe.

Sapphire: Sapphire is a gemstone, a variety of the mineral corundum, an aluminium oxide ().  It is typically blue in color, but natural "fancy" sapphires also occur in yellow, purple, orange, and green colors; "parti sapphires" show two or more colors.  The only color which sapphire cannot be is red – as red colored corundum is called ruby, another corundum variety.  Pink colored corundum may be either classified as ruby or sapphire depending on locale.  This variety in color is due to trace amounts of elements such as iron, titanium, chromium, copper, or magnesium.

UST Salinggawi Dance Troupe: The UST Salinggawi Dance Troupe (or simply "Salinggawi" or "SDT"), is the University-wide organization for dance and the official dance troupe of the University of Santo Tomas (UST).  The group is known for its versatility covering wide array of genre from performing arts to cheerleading, from contemporary to breakdancing.  The Salinggawi Dance Troupe is also the official cheerdance team along with the official pep squad and drumline - the UST Yellow Jackets of the University of Santo Tomas.  The group also performs for the halftime during the games of the UST Growling Tigers, the university's Men's Basketball team in the University Athletic Association of the Philippines.  The group is also the official team of the University to Skecher's Streetdance Competition.

Flick Colby: Flick Colby (born Felicity Isabelle Colby; March 23, 1946 – May 26, 2011) was an American dancer and choreographer best known for being a founding member and the choreographer of the United Kingdom dance troupe Pan's People, which was a fixture on the BBC 1 chart show "Top of the Pops" from 1968 to 1976.  Colby transitioned to become the full-time dance choreographer for the "Top of the Pops" dance troupes Pan's People, Ruby Flipper, Legs & Co., and Zoo (credited as "Dance Director"), from 1972 until 1983.

Bright Moon Song and Dance Troupe: Bright Moon Song and Dance Troupe (明月歌舞团) was a group founded by Li Jinhui from late 1920s to 1930s.  It is also translated as Bright Moonlight Song and Dance Troupe.

Ruby Flipper: Ruby Flipper were a multiracial, mixed-sex dance troupe who performed dance routines to songs in the UK Singles Chart on the BBC television series "Top of the Pops" in 1976.

Pan's People: Pan's People was a British TV dance troupe most commonly associated with the BBC TV music chart show "Top of the Pops" from the late 1960s to the mid-1970s, however they also appeared on numerous other TV shows in the UK and Europe.

Legs &amp; Co.: Legs & Co. were a dance troupe created in 1976 for the BBC's weekly Top Of The Pops programme, performing over three hundred times on this show by the time of their last performance in 1981.  The group then continued for four further years on tour.  The six-girl dance troupe replaced Ruby Flipper on Top Of The Pops, representing a reversion to the earlier all-female format for troupes on this show, and covering the time period where the disco, punk and new wave music fashions were at their chart peak.

Supporting paragraphs: Flick Colby Legs &amp; Co.
Answer: Top of the Pops