It was tough being a communist in Ireland in the 1940s. All card-carrying members were followed by the Special Branch, tended to be boycotted by the establishment and were refused jobs.
Thomas O'Brien knew all this. He had returned from fighting against fascism with his comrades in the International Brigade in Spain.
As a vocal and proud communist and poet, he was faced with certain unemployment. Perhaps influenced by Orwell's Homage to Catalonia, he swapped his sword for a pen and set up his own business. He was a printer - but his mission was produce biographies of Irish radicals, socialists and republicans, such as Erskine Childers and Peadar O'Donnell, men largely ignored by Ireland's intelligentsia.
The books were conceived, written, edited and printed - but getting publicity and sales was harder. In 1974, Thomas and his son Michael formed a publishing company, The O'Brien Press, and proceeded to change all that.
The first book produced and sold by the fledging business was an autobiography by leading IRA man and writer Eamonn MacThomais - who at the time was a guest of the nation in Mountjoy. The same year O'Brien Press was formed, Thomas dropped dead from a heart attack, leaving Michael to carry on the publishing firm alone in the family home.
Michael's son Ivan remembers a childhood surrounded by books and the excitement of running a business from home. All phone calls during working hours had to be answered 'O'Brien Press' and stuffing envelopes was a common family chore.
"Aged eight, I decided to follow Dad into the family business," says Ivan. "I created a magazine and printed copies. I had a cardboard suitcase but I even managed to sell copies to Hodges Figgis."
Ivan's path into the family business then took a slight detour as he discovered computers and his own internal 'geekiness'. He first studied Theoretical Physics in Trinity before committing to a PhD in Astrophysics. At the same time, he was helping his father navigate the business into modern times, learning how to typeset on a computer and working for the press on evenings, weekends and holidays.
There was no pressure - but once he had his PhD, Ivan had to make a decision.
"The world of physics is inhabited by very passionate, gifted people. I loved the work but I recognised there were always going to be more talented people than me who were prepared to sacrifice more than I was for careers in this space. I decided to work full-time in the publishing business instead."
As Ivan donned his publishing hat, he was met with the cry that books were dead.
"Every year, some new voice repeats that line and yet the death knell for printed books has not been heard. If anything, printed book sales are on the increase again."
Of course, the world of books is changing rapidly. Currently, some 8pc of O'Brien sales are ebooks, selling in over 80 countries in the last year. While the Kindle and comparable reading devices created a huge surge in digital reading, this has flattened out, says Ivan.
"Anyone who is going to read ebooks has already bought their device and is used to buying ebooks - so that surge in popularity stabilised. I welcome the emarket, obviously,
"I mean, I've sold thousands of ebooks in Australia and New Zealand - markets I would never have cracked with just physical books. For a small independent publisher, it makes a big difference to our bottom line."
O'Brien Press now employs 18 people and has over 750 books available by over 300 authors. The content is predominantly Irish - in terms of authors and theme - with some exceptions.
As an independent producer, Ivan argues that it is not ebooks that pose the biggest challenge, but the huge amount of free content now available and the concept that exposure is more important than getting paid.
"We've seen the high-profile tussle between Taylor Swift and Apple, with Swift sticking to her guns," says Ivan. "As a publishing house, we need to convince people that what we create are complex, challenging and beautifully crafted books.
"And that people will want to pay money for them. The dumbing-down of the entertainment industry - of which we are part - is the biggest obstacle for us. Just because anyone can produce and distribute content cheaply does not mean it's the right thing to do. Quality has to be at the heart of it."
Some developments - such as ebooks - have benefited O'Brien Press, and others - such as audio books - had revitalised failing areas. O'Brien Press had several books on audio cassettes and this market had dried up. But now O'Brien Downloadable audio has revitalised this area, so old tapes have been converted to MP3 and CD. The flagship products are Brendan O'Carroll's Mrs Brown's Boys trilogy.
O'Brien has a turnover of €2m in 2014. It was hit by the recession in 2008 when books became the victim of decreased disposable incomes. That hit was compounded the following year by the perversely antiquated sales model operated between printers and bookshops: all books are sold on a sale-or-return basis and unsold books can be returned for full credit after many months.
This happened in 2009 when returns soared and new sales stalled.
"It was a very painful double-whammy," says Ivan. "However, since that hit, sales have crept up again. We have a very loyal following and very loyal staff and I am glad to say business is improving again."
O'Brien is Ireland's leading publisher of children's books, which have also weathered the storm.
"Children's books travel well," he explains. "Children are very open to great stories, no matter where they come from, and this is definitely a growth area for us. Also, being Irish opens doors. At a book fair in the States some years ago, two buyers heard the accent and stopped to talk. That resulted in thousands of new sales over the years. And they only stopped because of the Irish accent."
O'Brien takes his job of producing beautiful Irish books seriously. He is just back from Brussels, where he was lobbying the Irish MEPs on behalf of the book industry to maintain copyright laws.
"The move to undermine copyright and increase the power of patents is an enormous challenge to all creative industries, primary driven by huge software companies. Threats to publishing come from all directions."
So far, O'Brien Press is succeeding. Book sales are up and technology has extended the global markets. Ivan is quietly confident he will continue to succeed but will his two children enter the family business?
Only time will tell, according to Ivan - but they may want to get a PhD or two first.