Background: The Seekers are an Australian folk-influenced pop quartet, originally formed in Melbourne in 1962. They were the first Australian pop music group to achieve major chart and sales success in the United Kingdom and the United States. They were popular during the 1960s with their best-known configuration as: Judith Durham on vocals, piano, and tambourine; Athol Guy on double bass and vocals; Keith Potger on twelve-string guitar, banjo, and vocals; and Bruce Woodley on guitar, mandolin, banjo, and vocals. The group had Top 10 hits in the 1960s with "I'll Never Find Another You", "A World of Our Own", "Morningtown Ride", "Someday, One Day" (written by Paul Simon),
Context: In March 1967, The Seekers returned to Australia for a homecoming tour, which included a performance at the Sidney Myer Music Bowl in Melbourne, attended by an estimated audience of 200,000. Guinness Book of World Records (1968) listed it as the greatest attendance at a concert in the Southern Hemisphere. Melburnians were celebrating the annual Moomba Festival, a free community festival, and many thousands were enjoying other attractions but are included in the crowd estimate. The Seekers were accompanied during their 20-minute set by the Melbourne Symphony Orchestra, conducted by Hector Crawford. Film of their appearance was incorporated into their 1967 Australian television special The Seekers Down Under, which was screened on Channel 7 and drew a then record audience of over 6 million. It was also screened in the UK on BBC1 on 24 June 1968, and repeated on 27 December 1968. In January 1968, on Australia Day, in recognition of its achievements, the group was named joint Australians of the Year - the only group to have this honour bestowed upon it. They personally accepted their awards from John Gorton, the Prime Minister of Australia, during their tour. During this visit, the group filmed another TV special, The World of the Seekers, which was screened in cinemas before being screened nationally on Channel 9 to high ratings and is in the Top 10 most watched TV shows of the 20th century in Australia. During the New Zealand tour on 14 February 1968, Durham approached the other group members to announce that she was leaving The Seekers to pursue a solo career and the group subsequently disbanded. Their final performance, on Tuesday 9 July, was screened live by the BBC as a special called Farewell the Seekers, with an audience of more than 10 million viewers. The special had been preceded by a week-long season at London's Talk of the Town nightclub and a live recording of one of their shows was released as a live LP record, Live at the Talk of the Town. It reached No. 2 on the UK charts. Also in July, the compilation album The Seekers' Greatest Hits was released and spent 17 weeks at No. 1 in Australia. It was released as The Best of The Seekers in the UK and spent 6 weeks at No. 1 in 1969, managing to knock The Beatles' (White Album) off the top of the charts and preventing The Rolling Stones' Beggars Banquet from reaching the top spot. The album spent 125 weeks in the charts in the UK. CANNOTANSWER
Question: why did it have this honor?

Answer:

in recognition of its achievements,