It's the 'other' tenor, Jose Carreras, snatching a few minutes from rehearsals for his new production of Fedora to pop in on an old colleague. 'I've come to see if there are any oranges or champagne.'
It's an in-joke between friends. The oranges refer back to the old Covent Garden production of Carmen, in which Carreras used to sing Don Jose. 'In Act 3 we used to go off together through a trap door. When we got to the bottom, the stage manager was always there with three oranges - one for John Dobson, one for Carreras and one for me.' An in-joke in itself, of course - punning the Seville setting of Bizet's tragic corrida with the title of Prokofiev's farcical opera, The Love for Three Oranges.
As for the champagne, that's a knowing nod at the 'third' tenor, Placido Domingo (who arrives at Covent Garden tonight to take over as Don Jose in the current Carmen run). 'We were in Un ballo in maschera together, years ago. He was singing Renato and I was singing the primo judice. It isn't a long part and it's over early, but I always like to say goodnight anyway. So, on the first night, I popped my head round Domingo's dressing- room door. 'But aren't you staying for the champagne?' he says. And then I noticed that the old, cracked washbasin in the corner was packed with ice and bottles of champagne. 'I'm sorry,' I said. 'I've got to get home to my family.' So he opened a bottle just for me. It's a bit of a running gag between Carreras and me. 'What about this then, star?' I'll say to him. 'What about my champagne?' '
So who is this mystery tenor who swaps drinks and jokes with the likes of Carreras and Domingo? You won't recognise his name, but if ever you've been to Covent Garden in the past 20-odd years, you're almost bound to have seen him - whether whiling away sleepless nights in Old Peking as the third masked minister from the left in that courtly trio - Ping, Pang and Pong - from Puccini's Turandot; or, as a dandified Monsieur Triquet, apostrophising a blushing young 'Ta-ty-a-na' on her nameday in Tchaikovsky's Eugene Onegin; or even, as he will be again tonight, conveying contraband across the Spanish mountains as a rollicking Remendado to Domingo's desperate Don Jose.
And while he can certainly turn in a dangerous Spoletta, almost a second Scarpia in waiting, for Tosca, or drink any other Missail under the hostess's table in Mussorgsky's Boris Godunov, his sympathetic stage presence makes him the perfect shoulder for other cast members to cry on. No other tenor is better as Beppe, the hapless Harlequin figure who tries to stop the commedia turning into tragedy in Leoncavallo's I Pagliacci, or as Nick, the philosophical bartender who makes sure his boss, Minnie, rides off into the sunset with the right hombre in Puccini's original horse opera, La fanciulla del West (returning to Covent Garden in July).
Gifted with a distinctive voice - high, fluting, perfectly poised, clearly enunciated, bright as a bell, liltingly Irish - he is at once always recognisably himself and unfailingly capable, in his few brief moments on stage, of creating a fully-formed character you can really believe in. His name? Francis Egerton, current king of the character tenors.
Not that he has always been just a bit-part-player. He began his working life as a machine tool setter, having come over to England from his native Cork at the age of 16 and settled in Wallington, Surrey, where he lives to this day. There, inspired by old recordings of Gigli and Bjorling, he began singing with local amateur operatics. After national service, he never really settled back into engineering and drifted instead into a variety of other jobs, ending up running an office for Peugeot UK. But he knew there was more to life than selling cars. 'I suppose, underneath it all, I wanted to sing, but of course I didn't have the courage. And then one morning I just woke up and said: 'Frank, you've got to get this out of your system.' And, of course, I never did.'
With the bravado of the beginner and the benefit of only a handful of lessons, he went along and auditioned for the lead in a London production of Rossini's The Italian Girl in Algiers. This being real life rather than opera, he didn't get the part; but he did get into the chorus. After that, one thing seems to have led to another. After three summers in the Glyndebourne chorus, supplementing his earnings with stints as a taxi-driver and a telephonist, he was given his first solo break as Goro, the marriage-broker in Madama Butterfly, by Scottish Opera, before being offered a principal's contract with Sadler's Wells (now English National) Opera, where he sang for five seasons, specialising in high-flying Rossini tenor roles like Lindoro, the very part he had failed to land in that Italian Girl only a few years before. He made his Covent Garden debut, 23 years ago this month, as a late stand-in for a lost voice, playing Osric in Humphrey Searle's long-forgotten Hamlet. And he's been there ever since.
He claims not to know how many roles he has in his repertoire, but has no problem naming the shortest - Streshnev, the herald in Mussorgsky's Khovanshchina, who comes on to announce Tsar Peter's pardon of the rebellious Streltsy Guards: it's only a cough and a spit to sing 'but has the most incredible entry and exit, preceded by a big brass band'. And the longest? 'Mime, without a shadow of a doubt.' He remembers his panic on first trying to learn the part of the murderous Nibelung dwarf in Wagner's Siegfried for Scottish Opera: when your longest role to date has been Nemorino, clocking in at around 40 minutes' music, tackling a character who, in Act 1 alone, never leaves the stage for 90 minutes was quite a challenge. But physically, of course, he's made for the part, and it's a small scandal that he's never been asked to do it at Covent Garden. Temperamentally, though, it's Nemorino, the lovesick swain in Donizetti's L'elisir d'amore, to whom he feels closest. 'The whole character of the fellow - the pathos, the indecisiveness, the sort of simplicity of the man - is very much me. I don't know if you'd agree?'
Recently his acting abilities have taken him off the opera stage on to the screen. He played a small scene with Bob Hoskins in the film of Brian Moore's The Lonely Passion of Judith Hearne and more recently appeared as the Cantor, the director's on-screen alter-ego, in Peter Greenaway's Baby of Macon, where he not only had the job of creating an ethereally unworldly voice for the saintly babe itself, but had to devise his own vocal settings of Greenaway's texts. He enjoyed the work more than the film: 'Quite horrific, wasn't it? One of my sons - and he's a keen Greenaway fan - went and even he said he only stayed out of duty.'
He'd do more straight acting if he wasn't in such worldwide operatic demand. Earlier this year, he had to turn down an offer to play Feste in a new RSC Twelfth Night directed by Ian Judge, who had worked with him on a Los Angeles Butterfly a few years ago. 'But I was absolutely over the moon. What a tremendous honour - just to be asked] It was almost like getting a knighthood.'
Yet, in the long run, his acting abilities may even have counted against him. As Stephen Arlen, former managing director of ENO, once told him, 'It's often easier to cast at the top than to bolster the middle.' And, as he accepts, 'Because they know I can act, some people may have thought, 'Give him a one-liner because he'll make that one line tell.' ' Yet when all is said and done, he still counts himself lucky to be doing a job he loves - 'and to be getting paid for it'.
But does he never dream about Domingo going sick and having to take his place? 'That's never been a fantasy of mine. Yes, I've thought over the years that I'm better than I've been given credit for. But when you're 5ft 4in tall, balding and all the rest of it, you start at a bit of a disadvantage. If you're 6ft tall, with black curly hair, handsome and slim, you're two-thirds of the way there. With the best will in the world, I can't ever look like Domingo.'
Carmen: in rep to 20 May (071-240 1911)