Country Club 51 Tommy Duncan after Bob Wills

Stephen Thomas Erlewine writes informatively about Tommy Duncan on allmusic.com.
 

As the lead singer for the classic lineup of Bob Wills' Texas Playboys, Tommy Duncan was the definitive Western swing vocalist. Crossing the smooth croon of Bing Crosby with the twang of Jimmie Rodgers and the bluesy inclinations of Emmett Miller, Duncan had a warm, distinctive, and welcoming voice that helped the Playboys cross over to a wider audience. Not only was he a wonderful, trendsetting vocalist, Duncan also wrote many of the Texas Playboys' biggest hits, including "Time Changes Everything," "Stay a Little Longer," "Take Me Back to Tulsa," "New Spanish Two Step," and "Bubbles in My Beer."'

Duncan split from Wills, or more accurately, was fired  in 1948.  "Gambling Polka Dot Blues" was his one big hit on his own. In the 1960s, Wills and Duncan reunited for a while and Duncan then continued an independent career.