ZD2KHK/NC 1961 Nigeria
That is an interesting card. Mubi is in Nigeria right on the Cameroon border. Nigeria changed its callsign from ZD2 to 5N on 1/1/1961. All my ZD2 cards are 1960 and before. All my 5N cards are 1961 or later. View the cards from Ted Howell, one from 13/8/60 as ZD2GUP and another one dated 1/1/61 as 5N2GUP. Patrick's card ZD2KHK/NC dated 1961 doesn't follow protocol and should have been a 5N. Perhaps he operated with his ZD2 before reassigned a 5N or perhaps the British Trust Territory extended across the border into Cameroon. Maybe he just didn't care about the prefix change.
QSL Patrick Rigg Collection
Info courtesy of K8CX