I know this is a bit of a dredge of an older topic, but considering;
5.105 What does a commercial pilot (aeroplane) licence authorise a person to do?
(1) A commercial pilot (aeroplane) licence authorises the holder of the licence: (a) to fly a single pilot aeroplane as pilot in command while the aeroplane is engaged in any operation; and
(b) to fly a multi-pilot aeroplane as pilot in command while the aeroplane is engaged in any operation other than a charter operation, or a regular public transport operation; and
(c) to fly an aeroplane as co-pilot while the aeroplane is engaged in any operation.
5.166 What does an air transport pilot (aeroplane) licence authorise a person to do? (1) An air transport pilot (aeroplane) licence authorises the holder of the licence to fly an aeroplane as pilot in command, or co-pilot, while the aeroplane is engaged in any operation.
How many of those logging co-pilot time here in somthing like a Chieftain or C400 series were sure their "Captain" held an ATPL?