On the other hand, this person I mentioned it to might keep it quiet, and I'd be all right. Should I come clean with my bosses and warn them that all hell might break loose, or should I trust to my colleague's discretion and hope nothing more comes of it
A Well, if you get away with this one, I'm ready to bet that you'll never do anything quite as daft again. You say it was your enthusiasm for the project that loosened your tongue, but I wonder. I suspect it was a combination of a pint too many and an urge to show off to a junior colleague. Not very grown-up, was it?
You also seem more concerned about the possible fallout for yourself than for your company. If you've put an important secret project at risk, you've betrayed your employers and everyone who works for them.
Happily, however, I'm pretty sure that your entirely justified sense of remorse has led you to have unjustified nightmares. What makes you think that this junior colleague has any contact with the trade press? Even if he has, would there be enough substance for them to run a story? And how could any leak easily be traced back to you? I'm delighted that you've scared yourself half to death, but now's the time to cool it.
Without making a huge issue out of it, simply remind your junior colleague that your confidence, if shared with anyone at all, could have serious consequences for all of you. Don't even mention the trade press: it probably hasn't even crossed his mind. You don't really deserve to get away with it, but my bet is you will.
Jeremy Bullmore has been creative director and chairman of J Walter Thompson London and a non-executive director of the Guardian Media Group; he is a non-executive director of WPP. Address your problems to Jeremy Bullmore at: firstname.lastname@example.org. Regrettably, no correspondence can be entered into.