A while ago on Heathrow Delivery.....
XYZ123: "Delivery, XYZ123 looking for clearance only......."
Me: "XYZ123, clearance is *********, and you have a slot time of 1230. Report ready."
XYZ123: "******** for XYZ123, and I'll let the flight crew know about the slot time when they turn up............"
Me: "....................................................... .okay"