The BBC has apologised after Jim Naughtie turned the airwaves blue on Radio 4 when he crashed the pips by swearing.
On the final beep the presenter was heard to whisper "shit" before launching into the news headlines on the flagship Today programme.
Nick Robinson, who began his new role on the show's presenting team today, tweeted a few minutes later: "Looks like being one of those days on @BBCr4today!".
It is not the first time Naughtie has let an expletive slip on the early-morning programme.
The presenter apologised in 2010 for an embarrassing verbal trip up over the name of cabinet minister Jeremy Hunt, replacing the first letter of his surname with a ''C''.
The on-air stumble sent the broadcaster into a coughing fit, and attracted a slew of emails from listeners who were either amused or angry.
Naughtie proceeded to interview Mr Hunt without incident, but later issued several apologies for his ''Spoonerism'' - a reference to Dr William Spooner who was notorious for inappropriately switching letters between words.
The latest incident comes as Robinson began his new anchor role after taking time off to recover from surgery and chemotherapy to treat lung cancer.
Robinson now receives daily coaching to help with his voice after one of his vocal cords was left damaged following the treatment.
"Apologies for croaky first day start on @BBCr4today. Been a long time off!" he added.
Robinson spent a decade fronting the BBC's political coverage but has moved to the early-morning slot to replace Naughtie, who will become a special correspondent.
A BBC spokesman, who confirmed that Naughtie was responsible for the slip, said: "The Today programme was live on location from Paris and, as with any live broadcast, occasionally slip-ups may happen. We apologise to listeners for any offence caused."