In 1970, Clannad signed a recording contract with Polydor Records after they came first in the annual Letterkenny Folk Festival. However, the label initially refused to release their music as they had little faith in their proposed album with songs sung in English and Irish. Their debut album, Clannad, was recorded at Eamonn Andrews Studios and is formed of arranged Irish songs, including a cover of "Morning Dew" by Bonnie Dobson, and original material. Following the album's release in 1973, Clannad took part in the heat stages of the 1973 Eurovision Song Contest for Ireland with "An Phairc" from Clannad as their entry. The band released Clannad 2 as their second studio album on Gael Linn Records in 1974. To produce the album the band hired Donal Lunny, founder of the Irish bands Planxty and The Bothy Band. Like their first release, Clannad 2 features a mixture of English and Irish songs, this time with Lunny and Bothy Band members on additional instruments.  Clannad released their third album Dulaman in 1976. The album is named after the Irish folk song "Dulaman" which became a fan favourite at Clannad concerts. Dulaman was recorded at Rockfield Studios in Wales and is their first album produced by Nicky Ryan. They supported Dulaman with their first tour of Europe which they completed in 1976, during which a standing ovation they received after an extended rendition of "Nil Se'n La" convinced them to continue with Clannad full time. Dates from their 1978 tour of Switzerland was released in the following year as Clannad in Concert. Also in 1979, Clannad underwent a 36-date tour of North America, the most extensive by an Irish band at the time.  In 1980, Clannad became a six-piece band following the addition of Enya Brennan on keyboards and additional vocals. Ryan wished to expand the group's sound with vocals and electronic instruments and invited her to join. Enya's first recordings with the group were made as a guest musician for their Crann Ull (Irish for Apple Tree), their fifth studio album recorded in Cologne, Germany and released in 1980 on Tara Music. "Ar a Ghabhail 'n a 'Chuain Domh" featured a particularly full band arrangement reflective of their live jams at the time. "La Cuimhthioch Fan dTuath" showed the first hints of the more atmospheric side of the band's arrangements.  By the time Clannad entered Windmill Lane Studios in Dublin to record Fuaim (Irish for Sound), Enya had become a full time member. The album displays the group's further experimentation with electronic instruments, and Enya is featured on lead vocals on "An tUll" and "Buaireadh an Phosta". Neil Buckley plays the clarinet and saxophone plus Noel Bridgeman on percussion and Pat Farrell on electric guitar. Fuaim was released by Tara Music in 1982. After a further European tour, Enya left the band as she wished to pursue a solo career and felt constricted as a member of a band. Ryan followed suit with his wife and other manager Roma Ryan, which caused a rift between the two groups for a short time.  In 1982, the now five-piece Clannad signed to RCA Records. They then accepted an invitation to record a song for Harry's Game, a three-part television drama depicting The Troubles in Northern Ireland. Ciaran, Pol, and Maire got together and wrote "Theme from Harry's Game". The song became a commercial success upon its release as a single in October 1982, peaking at number 2 in Ireland and number 5 in the UK. It remains the only UK hit single to be sung entirely in Irish. From 1983 to 1987, rock band U2 used the song at the end of every concert. Following their newfound success with "Theme from Harry's Game", Clannad included the song on their seventh studio album, Magical Ring, released in 1983. The single and album marked the start of their international career, and Magical Ring became their first to be certified gold by the British Phonographic Industry (BPI).  After Magical Ring, Clannad were commissioned to score the 26-episode drama series Robin of Sherwood, aired from 1984 to 1986. They once again began to stretch themselves, creating music for a range of characters and events. For the first time in the career, the album was recorded in its entirety in English. The soundtrack was released in 1984 as Legend and won the band a BAFTA award for Best Original Television Music, the first Irish band to win it. In 2003, Clannad revealed that there were other pieces recorded for the third series of Robin of Sherwood that were not included on Legend, yet the master recordings have yet to be found.  In 1985, Clannad released Macalla (Irish for Echo) which was recorded in Switzerland, England, and Ireland. It contained all original material except one traditional song and yielded the group a hit single "In a Lifetime", a duet with U2 singer Bono which begins with Maire being heard teaching Gaelic to Bono during the introduction. The album features numerous backing musicians who have continued to tour with them, including ex-King Crimson saxophonist Mel Collins, Moving Hearts' guitarist Anthony Drennan, and drummer Paul Moran. Also on board was producer Steve Nye, who oversaw the pop-flavoured "Closer to Your Heart" and the ballad "Almost Seems (Too Late to Turn)" and became hit singles, the latter serving as the Children in Need charity single in 1985.  Sirius was released by RCA in 1988 and was recorded in Los Angeles with rock producers Greg Ladanyi and Russ Kunkel, the drummer for James Taylor's band. The album included a duet with Bruce Hornsby and guest appearances by Steve Perry and J.D. Souther. The title track was Pol's encouraging call to the environmental movement, and to the Greenpeace ship of the same name. "Something to Believe In" features Hornsby on vocals and keyboards. Completed with the help of some of the biggest names on the Californian rock scene, Sirius was another different creation, just like their previous 3 albums. Received with critical apprehension, Sirius was initially, stoutly defended by the band as a change, but since then members have expressed their disappointment with the album. In 1989, Clannad embarked on their first worldwide tour.  Between 1988 and 1991, Clannad were involved in side projects including Atlantic Realm (1989) and The Angel and the Soldier Boy (1990). Atlantic Realm was a small album made for a BBC documentary about the Atlantic Ocean. The recording was mainly instrumental as their voices as instruments. The Angel and the Soldier Boy was a half - hour animation without voice overs, with the music telling the story. Both albums proved to be a minor success, and also demonstrated once again that Clannad were one of the most acclaimed soundtrack artists in the music industry. Two greatest hits albums were released at around this time:  Past Present RCA, which to date is the only "greatest hits" compilation so far by the band to include any new tracks: "The Hunter" and "World of Difference". This album also included tracks from Magical Ring, Macalla, and Sirius.  The Collection k-Tel, re-released in 1996 under the label's Celtic Collections series. Unlike Past Present however, it also included five earlier tracks from their more traditional Irish period.  Pol initially left the group to pursue a solo career and work with the WOMAD (World of Music, Arts and Dance) organisation in Britain. He released a trio album in 1993 with Guo Yue and Joji Hirota under the new name Trisan. The true reason for Pol's departure is unknown; being a family band, very little information is released about personal and professional relations about and between the members. Pol rejoined the band in January 2011, when Clannad performed at Temple Bar TradFest. Initially a single concert, it was extended with an extra two nights.

Answer this question "What was a career highlight during this time?" by extracting the answer from the text above.
Two greatest hits albums were released at around this time: