Australia Post has “apologised for the inconvenience” after delivering a postcard from a South Pacific island a full half-century after it was sent.

An Adelaide couple found the postcard from the French Polynesian island of Tahiti in their letterbox, postmarked 1966.

The Adelaide Advertiser reported that the “slightly faded” postcard was addressed to “Robert Giorgio” from “Chris” in 1966.

It showed a scene from the Papeete waterfront, including the distinctive Bloc Donald building, which featured on many postcards of the 1950s.

Chris said he was “enjoying myself greatly”, despite the “very humid” weather.

The stamp on the postcard cost 13 francs.

Wattle Park resident Tim Duffy, who found the postcard beneath a water bill on Monday, believed Giorgio may have been the property’s original owner. Duffy and his wife Claire have both been contacted for comment by Guardian Australia.

“It is clear something went wrong 50 years ago after the postcard was posted in French Polynesia, and we apologise for the inconvenience,” an Australian Post spokesman told the Advertiser.

“Australia Post takes great pride in the timely, safe and efficient delivery of mail and we are confident that the vast majority of mail and parcels arrive on time.”

Vintage postcards showing similar scenes are available to buy cheaply on eBay.