In 1955 he would have a No.1 hit on the pop music charts in the United Kingdom with the theme song to the operetta "Rose Marie." With nineteen weeks in the charts and eleven weeks at the top of the UK Singles Chart, the song set a record that lasted for 36 years. In 1956 he became the first-ever country music singer to perform at the London Palladium. Soon after, Whitman was invited to join the Grand Ole Opry, and in 1957, along with other musical stars, he appeared in the film musical "Jamboree". Despite this exposure, he never achieved the level of stardom in the United States that he did in Britain, where he had a number of other hits during the 1950s. Throughout the early 1970s, he continued to record and was a guest on Wolfman Jack's television show "The Midnight Special". At the time, Whitman's recording efforts were yielding only minor hits in the US. The mid-1970s were a successful time for Whitman in the UK Albums Chart. In 1976 a compilation album, "The Very Best of Slim Whitman", was number one for six weeks, staying seventeen weeks on the chart. Another number one album followed in 1977 with "Red River Valley": four weeks at number one and fourteen weeks on the chart. Later the same year his album "Home on the Range" made number 2 on the chart and amassed a chart stay of thirteen weeks, only to be kept from the top place by "20 Golden Greats" by the Supremes.