How We Met: Guy Henry & Hugh Bonneville

Guy Henry, 50

A stage and screen actor, Henry is best known as the aloof surgeon Henrik Hanssen in the BBC drama 'Holby City'. He was also in the most recent 'Harry Potter' film. He lives in London with his partner and son

We were two young things lucky to have our first roles at the National Theatre in 1990. Hugh was doing a period play and I remember him coming to the backstage bar after a production, this striking, broad-shouldered guy with bright-blue eyes, looking very imposing, but wearing this stupid tweedy period outfit.

We were both cast in a production of School for Scandal; I was the backbiting fop, Hugh the lovable rogue. It suited him beautifully as he was quite frightening in real life: he has an outward gruffness and commanding manner – but underneath there's a softness and a twinkle.

We were then both offered roles as part of a season at the RSC in Stratford-upon-Avon, so I plucked up the courage to ask Hugh if we might share digs. We ended up in this twee suburban house in the outskirts of Stratford and it was bloody good fun. He's not as much of an old-fashioned hell-raiser as I am, but he joined in with good grace.

If you live with someone for a year doing stressful, hard work – four plays, one after the other – it's hard not to become close. Our big difference was punctuality. He'd get very cross when I was late for things, which was often. I arrived late for one matinée and my understudy was getting ready to come on. I was thinking, "He's really going to tell me off," and he came thundering down the corridor, in a purple wig, red with make-up, roaring at me.

After Stratford we never lost touch and we delight in each other's good points and foibles. He's always been very good at getting work, and people appreciate his intellect, versatility and meticulous preparation. I have a more doolally quality and I've had a much more erratic career. I sometimes feel I'm a mess and don't know anything, but Hugh does – or he pulls off not knowing better than I do.

We're godfathers to each other's children and he's the one I call if I have something I need to ask about: schooling for my son, or just to find someone to accompany me to the tailor. Things are going incredibly well with Holby City, but I don't quite see myself on a par with Hugh – he's having a golden period.

Hugh Bonneville, 47

A TV and film actor, Bonneville is best known for playing the patriarch Earl of Grantham in 'Downton Abbey' and films including 'Notting Hill' and 'Iris'. He lives in Sussex with his wife and son

The first time I saw Guy was at the backstage bar at the National in 1990. He was holding court after a show, with five or six people. I saw this beanpole with hooded eyes and luxuriant voice speaking with utter confidence about life, art and everything; mainly about him. I felt overwhelmed, so I sat away in the corner like a schoolboy.

Shortly after that we were selected to appear in the play School for Scandal together. On stage he has this natural comic edge, but he can be deeply frustrating to work with. You might be fine-tuning your performance, but with Guy you never know what's coming next and it can throw you off balance. At the end of the year we were both cast in the RSC in the same season in the same four plays, and in one we were a double act; it was a prospect I was rather scared of.

We both had to find somewhere to live, so we sidled up to one another and talked about living in digs. Our den became party central; everyone from the local pub often came back to ours for drinking, smoking and playing music till 3am. To my utter surprise, considering we are so different, that year in Stratford was the happiest experience I've ever had.

He taught me a lot about improving my skills – he's not a great fan of rehearsal, but he loves playing off the audience and he has an ability to be spontaneous, so it's a joy being on stage with him, even if you do want to slap him sometimes.

Guy is a professional hypochondriac, and he's so stick-thin, as he runs off adrenalin. And for someone who has to have everything on his dressing-table neatly arranged, his time-keeping is phenomenally chaotic. He has been professionally late a number of times, but he manages to get away with it. I'm more nervous about being late than anything, and as he's touched 50, I'd like to think he's beginning to learn that punctuality is something you need doing this job.

We both understand how vague the notion of success or continuity is in this business, so it's never been an issue for either of us – we're all just lurching from job to job. Like me, he now has a son and different responsibilities have come into play, so now his family come and stay with us in Sussex – though the last time we were supposed to meet for a picnic, they missed most of it as Guy had overslept, so really nothing's changed.

Guy Henry appears in 'Holby City', Tuesdays at 8pm on BBC1. 'Downton Abbey' returns in the autumn