The name of The Mike Cotton Sound might be most familiar from the group’s role backing Mary Hopkin on her debut album Post Card, or for supporting The Kinks on Muswell Hillbillies.  But the band, led by trumpeter and multi-instrumentalist Mike Cotton, actually traveled a diverse musical road throughout the 1960s, a trajectory chronicled on RPM Records’ expanded edition of the band’s 1964 long-player, The Mike Cotton Sound. Leader Cotton had scored his first hit in 1963 with “Swing That Hammer,” with his group The Mike Cotton Jazzmen.  The Jazzmen had flourished…