The Mamas and Papas' single ‘Monday, Monday’ was at its peak British chart position of #3 during this week in 1966. It had previously reached #1 on the US Billboard Hot 100 (their only chart topper there). This was the perfect follow-up to their breakthrough hit 'California Dreamin'' and established the group as a serious force. The song is a joy right from the opening 'bah da bah da da da' vocals (although most of the group apparently didn't think too much of it at first), and it has endured as a '60s classic.