Gerard Murphy is looking back.

As the Irish actor returns to the Citizens Theatre in Glasgow for the first time in 14 years to appear in Samuel Beckett's solo play, Krapp's Last Tape, it is an appropriate thing to be doing. Krapp, after all, focuses on an old man rewinding his past via reels of tapes on which he's charted his hopes, ambitions and subsequent disappointments ever since he was a young man. Not that Murphy had much in the way of failure during his time at the Citz, which began an intense three years in 1974, and continued intermittently until 1998, towards the end of what is now regarded as the theatre's golden era under the three-way artistic directorship of Giles Havergal, Robert David MacDonald and Philip Prowse.

With Krapp forming part of a double bill with another Beckett miniature, Footfalls, Murphy returns to the Citz at the end of incoming director Dominic Hill's first season, which has tempted other prodigals such as David Hayman and Cal Macaninch back to the Gorbals. As he sits alone in the foyer of a building he virtually lived in at the start of his career, Murphy is understandably reflective.

"Coming back here, it feels like coming home," he says, echoing the sentiments of both Hayman and Macaninch. "It is home to me in so many ways. It's where I started, and it's the most important theatre ever. Watching King Lear, it was like Dominic had sprinkled magic dust. It was like the best of the old times, but with new faces and young people alongside the old, in that wonderful mixture that I associate with here, and the tears came to my eyes.

"I just thought, how lucky am I to be back here. It's just a wonderful feeling to sit in this bar and think, my God, in a time when in England theatre is dying, theatre's very much alive here."

Being alive is at the core of Krapp's Last Tape, which, by Murphy's own nervous admission, "is one helluva thing to attempt".

"It's fantastic to be asked to try. I know it's just a man and a tape, but it's such a mix of humour, pain, anguish, loneliness and poetry. This man, he's profoundly alone. He's profoundly disillusioned. He's a randy old bugger, but he can't get it up any more, and we hear him 30 years before, with all those hopes he had, of a great career and a great novel, and this is a weird thing. Because here he is now, and he still has constipation, he still hasn't written the great novel, and he's still recording these tapes of where he is at any particular time.

"He's a tough old nut, this one, and yet there are strands of undoubted beauty in it that are sheer sentiment."

The last person to perform as Krapp in the Citizens, of course, was one of the men who first employed Murphy, Giles Havergal. "Giles brought something very personal to it," Murphy acknowledges, "but I'm a different kind of man, so I hope I can bring something of my own to it."

Murphy grew up in Newry, County Down, in Northern Ireland, and originally intended to become a musician. Naturally shy, he says: "I could see that if I went down that route I'd become more and more introverted, and I wanted to find a voice."

Thinking acting was "a night job" which he could fit around his studies, he approached his local theatre, where it was explained to him that it wasn't quite like that. Even though Murphy didn't hold what was then a compulsory Equity card, he got the job.

"What I didn't know was that they were looking for someone to play a mentally defective child, and this angelic-looking creature with long blonde hair, which I had then, walked through the door."

When someone suggested he attended one of the Citz's open auditions, Murphy arrived in Scotland equally naive, but again was offered a job. The first show of what was originally a three-month contract was Coriolanus, which, coming in the thick of the Citz's heyday as the raciest show in town, was "a fantastically exciting shock".

Over the next three years, Murphy played in Brecht, Shakespeare, Wilde and de Sade. His Citizens' swansong was supposed to be in Woyzeck, after which the company contracts should have been up. A tragic motorway accident involving a visiting company put paid to that, however, and a new play by MacDonald, Chinchilla, was rushed into production to fill the dark two weeks. An epic based around legendary impresario Diaghilev, in which Murphy played the title role, Chinchilla was an epic, if unlikely, hit.

"It was just another play as far as I was concerned, and I had no idea how it might affect things."

As a direct result of Chinchilla, Trevor Nunn, then in charge of the Royal Shakespeare Company, offered him the lead role in Juno and the Paycock opposite Judy Dench. While this didn't stop Murphy returning to the Citz to play Macbeth opposite David Hayman's Lady M as well as in a revival of Chinchilla, Murphy has retained an ongoing relationship with the RSC, where he is now an associate artist.

As well as bread-winning TV turns and cameos in big budget movies such as Batman Returns, Murphy has directed and translated French plays, but remains modest about his output. It's the Citizens he really wants to talk about, in terms of how his days there have informed his entire career. Two things in particular stick out.

One night after a show, rather than go for a drink with the cast, Murphy left intending to go straight home. Instead, he decided to pop into a pub in the Gorbals that he wasn't familiar with. On entering what became instantly apparent was something of a spit and sawdust rough-house, dressed as he was in late 1970s punky attire, Murphy instantly regretted his decision. When a couple of heavy types sauntered over and asked him if he was an actor, he thought his number was up. Such anxiety was heightened when they informed him the play he was currently in wasn't up to much, or words to that effect. When they suggested that the theatre should do more plays by Seneca, however, it became clear that they were Citz regulars, and a lively evening discussing the merits of Seneca, Wilde and others ensued.

If such an incident highlights just how much theatre can mean to its audience, Murphy's second observation is equally as telling.

"It's the only theatre where show-time at 7.30 is the most important time of the day. Half the people who work in some other theatres don't even know what's on. Here it's different, where the cleaners and everyone in the office know what's going on. I was shocked when I left here to discover that other theatres weren't like that."

Now he's back, however, Murphy can revel in such old loyalties. As for Krapp, unlike the man he's playing, Murphy is looking forward to it.

"I'm a big Beckett fan," he says, "but it scares the life out of me, trying to get the accuracy of emotion. It's exactly like a piece of music, in that it's a sonata for one man and a tape recorder, but it's not good enough to just be technically accurate. You have to get the emotion right as well."

Krapp's Last Tape and Footfalls is at the Citizens Theatre, Glasgow, from May 30 to June 9.