At the start of yesterday's Press launch in a rather cramped room in a swanky Aldwych hotel, he rubbed his eyes, as if in disbelief at his own announcement.
The new RST and Swan theatres will open on time, and on budget, in November, though his own pretty awful production of Antony and Cleopatra will be "revisited" in a down-sized Swan revival after Rupert Goold's Romeo and Juliet and David Farr's King Lear do the opening season honours next February.
It's one of the most attractive things about Boyd that he gives full credit to his colleagues and allows his chief associate, Greg Doran, for instance, such full rein; he's certainly like Peter Hall and Richard Eyre in that respect.
And as the Press corps bustled about, elbows sqaushed in, juggling little sarnies and a spoonful of salad, even Patrick Carnegy, who wrote the rudest review I've ever read of an RSC production -- he demolished Antony and Cleopatra in the Spectator -- was allowed to mingle unmolested.
Rupert Goold sported a summer suntan that would make the egregious David Dickinson -- of Dickinson's Real Deal on ITV -- look positively pasty-faced, while David Farr nearly choked on his own enthusiasm for a Katie Mitchell production he's seen in Germany of Miss Julie where the actors are obscured by the setting and swamped in technology.
I liked the sound of the pioneering "light block" in the new theatre, and of "comfortable buttocks" on re-upholstered seats in the Swan, but don't much like the sound of local amateurs invading the place: is there to be nothing sacred, or holy, about this new theatre? Evidently not. It's the new democracy, innit?
The architects explained their view that the old theatre was "hostile" and "turned its back on the town." More glass on the frontage and an opening up of the river walk are seen as ways of combating that problem, but I think the problem was always coming from the town itself, not the theatre.
Still, executive director Vikki Heywood has been on a sustained charm offensive locally for some years now, and the company is obviously confident that this has paid off, even if there is still the last £5m to raise.
The emphasis is still on the Stratford roots of the company, with the key issue of a permanent London home left on the back burner. Boyd sees the new theatre opening out to the whole of the West Midlands, with the RSC contributing £58m to the regional economy.
His proudest moment, he says, was the suggestion of a Stratford B&B manager that he should stand for mayor of the town. And once again he emphasised the key part the RSC Learning programme is playing in the evolution of the new RSC.
With the RSC coming out of the woods, it was high time I went back into them, catching up with the superb Regent's Park production of Sondheim's musical.
I can see why so many performances of Into the Woods have been lost to the rain this summer: there's absolutely no hiding place on the set of ramps and stairways, and one little shower must be a nightmare.
I can't help wondering if director Timothy Sheader hasn't missed a trick. Magnificent though it all is, and Soutra Gilmour's design uses the foliage and boskiness better than any show I've ever seen here, former director Ian Talbot once told me that even in the very worst of monsoon summers, he never lost more than seven performances all season.
Last night's packed audience was full of returning customers who'd been rained off before, and the scenes of rehabilitation at the box office were pretty chaotic, though I have to say the BO staff coped admirably under pressure, and the odd outburst of frustration.
There was the added diversion of Georgina Simpson, heiress and wife to Anthony Andrews, shepherding her four young charges between queues to see which would be served first, and then finding hubby in the sponsors' marquee in a bit of a huff.
The casting of the narrator as a young child is a stroke of genius, and the company is outstanding from top to bottom, led by Hannah Waddingham's facially deformed (why?) witch and Helen Dallimore's lovely Cinderella.
But the performance of the night for me is Mark Hadfield's as the baker, really touching and beautifully sung.
I think I was deeply affected by Into the Woods when I first saw it on Broadway because my own son was about ten years old and the piece is as much about childhood as it is about mortality.
Coincidentally, I first took him to see the RSC around the same time, when Mark Hadfield was a brilliant Dromio in a touring version of The Comedy of Errors in Carlisle.
When Hadfield's baker finally embraced the small boy narrator as the son he'd been fighting for all his life...well, you can imagine what feelings stirred within me on a night of magic and adventure in the park.