Quite sad news.
I was named after him, would you believe! Probably due to "24 Hours From Tulsa" being a big Top 10 hit at the time my mum was expecting me.....
I had the pleasure of seeing the man at Lewisham Theatre in March 1983. Even by then, at the age of 42, he was completely grey. But he was still cutting the mustard, and sounding just as good as he did in his '60s hits.
As Netspeaky says, "She's A Heartbreaker" was played on the scene at one point. It's the B-side of a 1968 release, "Yours Until Tomorrow".
Rest in peace.