Paul McCartney's Wings was one of the most successful acts the U.K. has ever produced and the mid ‘70s were certainly a commercial heyday for the group. The legendary Wings Over The World tour, starting in the autumn of 1975, took in a staggering 10 countries in just 13 months. Almost as relentless was the band's continuing stream of chart albums and singles. In April 1976 the Wings At The Speed Of Sound album was released and its signature hits "Silly Love Songs" and "Let 'Em In" extended their reign once again. It was the second of two albums to feature what many (Paul included) regard as the perfect Wings line-up, with the McCartneys and Denny Laine joined by guitarist Jimmy McCulloch and drummer Joe English. At The Speed Of Sound went on to become Paul's most successful American chart album spending seven consecutive weeks at No. 1 while in the U.K. it charted at No. 2, narrowly missing out on the top spot.