Evelyn O'Rourke was at home on Friday, 30 April, when she got the news that Gerry Ryan, her colleague, friend and mentor, had been found dead. The 38-year-old reporter, who is currently on maternity leave from RTE, was shocked and heartbroken, but she knew what needed to be done. "I knew I had to come in, I had to be here," she said. "He taught me everything I know about broadcasting, and everything I know about radio. He said to me that it could be the most amazing experience of my life, if I worked at it, which I did."

O'Rourke hosted two tribute programmes to the late presenter last week, hardly an easy task given the eight years that she spent working with Ryan as a roving reporter.

While she was visibly upset signing Gerry Ryan's book of condolences last Monday as husband John McMahon, the head of 2FM, hugged her, on air she was the consummate professional.

O'Rourke's composure during both three hour shows set a tone of restrained but deep sadness. "She gauged the mood; she wasn't over the top," one listener observed. "She empathised with those at home in their kitchen feeling very lonely and lostbut at no point did she break down."

Durndrum-raised (she still lives beside her mother Peigi, a retired school headmistress; her father Pascal passed away in 1998), O'Rourke started in RTE around the same time as Ryan Tubridy and his former wife Ann Marie Power, who are both good friends of hers. The third of four children, she studied drama and English at Trinity, where she realised she wanted to work in the arts or media.

She moved to Galway to work in film and television, which involved spending hours in her car and it was during this time that she first fell in love with radio She applied for the position of researcher for Radio One in 1998 and her first job was The Summer Show with Alan Short, where she worked alongside Tubridy. She then moved to The Gay Byrne Show for its last season, where she first started to report. "It was very intimidating, I was very young and very scared," she has said.

"At a meeting once a week you'd pitch your story and he'd look at you, almost looking straight through you and you'd be quaking in your boots because you just wanted him to approve. And he'd say something like 'What would housewives in Co Clare think of this?'"

After working on a series of shows, including Pat Kenny's, she joined The Gerry Ryan Show in 2003 and has grown up alongside it. "I was single when I started and I've gotten engaged, married and had a baby during my time here," she said.

Of Ryan, she has never been anything but admiring, describing him as a "cheeky older brother".

"I love being on air with him. I always come out on a great high. He still makes me laugh, which after seven years, I think is very good," she said in an interview.

"After all this time it still fascinates me how much Gerry's listeners adore him, particularly his core female audience. When they meet you it's like you're a messenger from the Messiah. They ask everything about him and how his kids are doing. I'm flabbergasted when they seem to know more about him than we do."

O'Rourke is very well regarded – by listeners, by the industry and in the media for her unflagging enthusiasm and genial personbility. At a talk she gave to transition students at Coláiste Iosagáin in Stillorgan (her alma mater), just two weeks before Ryan's death, she impressed both parents and students alike with her good humour and warmth. "She spoke about the importance of being independent but being open to the idea of falling in love and how it didn't matter if you were fat or thin," said one father. "My daughter said she made you feel like you were the only person in the room."

But she failed to impress some listeners to Liveline when she stepped in for Joe Duffy in February 2007. A debate on gay adoption drew complaints that O'Rourke had not challenged callers who were critical of interviewee Hermann Kelly, who had written an article criticising gay adoption and that she had clearly stated her own position in favour of gay adoption. The complaints were upheld by the Broadcasting Complaints Commission.

But this was a small blip in a career in which O'Rourke has proved herself to be a versatile broadcaster, whether that was 'cheerleader' to Ryan's 'ringmaster' in the makeover programme Operation Transformation or sitting in for Shane Lynch on The All Ireland Talent Show when he missed his flight.

Last year, she presented Girl Talk on RTE Choice, a series of interviews with female celebrities such as Amanda Brunker and Geri Maye.

It's been a fulfilling time personally for O'Rourke also – she gave birth to her first son, Oisin in December.

Describing Ryan as 'irreplaceable', her husband John McMahon said there was no contingency plan. "There was never a plan B for Gerry," he said.

In the wake of the national outpouring of grief, that much is clearly true but based on her performance last week, it's fair to say that O'Rourke stepped up to that challenge admirably.

Hero or Villain? Evelyn O'Rourke

High: An impressive CV counting top rating radio and TV shows ranging from The Gerry Ryan Show to The All Ireland Talent Show

Low: Being rapped on the knuckles by the Broadcasting Complaints Commission for lack of objectivity during a Liveline debate on gay adoption