Thanks sgtangel,
Changed my almost empty (still in tears that I had not sucked the last gasp out of the cylinder - a jock thing - hope you can commiserate) at Kilbirnie Street. today.
Phoned Calor (Kilbirnie Street) yesterday to be told I had to have an empty 6kg steel or Lite in order to purchase a filled Lite.
Phoned another Calor stockist, DeWaldens Ayrshire and was told the same.
I now find that Calor (Kilbirnie Street) have in their exchange policy booklet for staff guidance, a reference to 7kg Butane bottles being acceptable for propane 6kg gas-lite exchanges.
So happens I have a 7kg Butane empty, hoping to exchange for a 6kg propane lite tomorrow.
It all seems so difficult with Calor, ever changing parameters for gas purchases, not as if they are not a very profitable business, guess customers are the very most bottom line.