The summer of 1983 was a watershed in the lives of best friends Mary Phelan and Catherine Conlon, then aged 18. Joined at the hips for years during school, their lives were about to take very different paths.

Mary stayed in her hometown of Carrick-on-Suir, and would stay in Ireland, while Catherine moved to Brittany in France to work as an au-pair, never to live at home again.

For one year, the pair swapped long, detailed letters documenting growing pains, tales of Macra dances, Dynasty episodes, unrequited love, strange French cuisine and plenty of gossip.

Now, in the year the women both turned 50, the letters have been published as Dear Cathy, Love Mary.

Mary reread the letters after the death of her mother, Peggy, and felt compelled to share the stories with a wider audience.

“I used to ring my mother from 7.30pm to 8pm and when she died I started reading them from that time. It just brought me back to 1983 in Carrick. It was like I could remember the windows open in my bedroom, and I was writing the letters to Catherine,” explains Mary.

long letters

“We would write 14-15 pages of longhand and it took time to write those letters. If you didn’t have something to say, you’d go off and have a cup of tea or eat your dinner and come back to them. Now you’re inclined to shoot off a few messages in text, but back then you put thought into what you wrote.”

A reoccurring theme in the letters was Mary’s apathy toward her accountancy course in Waterford (though she is now head of finance at the Irish Stock Exchange) and Catherine’s difficulties with fitting into French life.

“College was all new to me. I was from a working-class background and had no role models who had third-level education.

“A lot of the people who I thought were stuck up were actually lovely. It was more to do with me being afraid of not fitting in,” says Mary.

“When you get older it doesn’t matter as much and you have confidence to do your own thing, but at the age of 18 you just want to be like everyone else. It was tough, but we really bolstered each other through the letters.”

As an emigrant, Catherine felt very lonely and displaced in France and her letters to Mary were an essential lifeline to her life at home.

“I felt very cut off. I moved away and didn’t know anyone. I didn’t even speak the language. If I had known then, I probably wouldn’t have gone. It was a complete shock,” she says.

“I remember getting there and not being able to call home. It’s so different now. I landed in Dublin Airport yesterday and I was able to post a Facebook status saying that I had arrived – my 900 friends knew I was in Ireland and it was raining.”

After her summer in France, Catherine returned to Carrick-on-Suir for a few days (during which time she and Mary hitch-hiked to Limerick to see Chris de Burgh) and realised she wouldn’t be able to settle at home. She would go on to live in the French Alp, before moving to California and then Oregon, where she now resides.

“Even though I was so happy to be with them, I was bored. I remember thinking after an hour, I’m ready to move on. The reality was that I wasn’t going to go back,” she says.

However, Mary and Catherine remained in touch and are still friends, even if much has changed since they were girls in 1983 and Facebook has replaced letters.

“I think when you’re 18, you think you’re old in your 20s. I’m in my 50s and I can’t get my head around it. The more you learn, the more you realise you don’t know. It is about the journey and not the destination,” says Mary.

Cathy agrees, recounting a memory from her last few days at home.

“It was right before I went to France, and Mary and I were walking around Carrick. We saw a pair of really old women talking on the street and you could tell that one of them had come back from the States. They were probably only 50, and I was thinking, look your one with the American accent. I thought, I’ll never be that old. That will never be me. But here we are, and it’s wonderful,” she smiles.

Published by Penguin, Dear Cathy, Love Mary is in bookshops now