The cider brand ran a poster campaign on the underground, in which a photograph of a man in an orchard was accompanied by text that stated "Feck off bees. We have beehives."
The ad said: "The beekeepers come and they leave the bees here, in the open orchards.
"I like to walk by the lake at lunch. The bees buzz my bald patch. We need the bees for pollination.
"Personally, I don't like bees. Thomas White Orchard Keeper".
The poster attracted one complaint who said the phrase "Feck off" was offensive, because it appeared on a poster and could therefore be seen by children.
Magners said the poster was part of a series intended to bring those local heroes to the fore and celebrate their contribution to the Magners story, using their own images and stories.
In its submission to the Advertising Standards Authority, Magners said the term "feck" had been in usage since the 1800s and, in Ireland, the term was used in informal, everyday colloquial conversation with different meanings.
They said the term could be used to mean "to steal", "to throw" or "to leave hastily".
The ASA noted that the use of the word "feck" in Britain had been popularised by the Channel 4's comedy series 'Father Ted' in which the drunken father Jack says it often when he declares his interests "drink, feck, girls".
While the word has a different meaning it is used in 'Father Ted' as a substitute for the word fuck in the same way as characters in the revamped 'Battlestar Galactica' use the word "frak".
The ASA concluded in its adjudication: "We also considered that the tone of the ad was not aggressive or threatening.
"We considered that the term 'feck' was unlikely to be seen as a swearword and the poster was therefore unlikely to cause serious or widespread offence to adults and was not unsuitable for a medium where it could be seen by children."