If Sir Tim Barrow was feeling any nerves on the day he would personally trigger Britain's historic exit from the EU, he wasn't showing them.
The 53-year-old British ambassador to the EU, bearded and wearing a waistcoat and dark suit, grinned at the media as he strolled in early to work at the British embassy on Wednesday.
An hour later Barrow, who has only been in the job since his predecessor quit in January, emerged holding a worn leather briefcase and hopped into a waiting Jaguar limousine for the five-minute drive to the European Council headquarters.
Inside the black briefcase was a ticking political timebomb -- the Article 50 notification letter signed the day before by Prime Minister Theresa May and delivered to Brussels on a Eurostar train from London.
On the short drive, Barrow could not have missed the monumental banner alongside the EU Commission's Berlaymont headquarters celebrating the 60 years since the Treaty of Rome, the EU's founding document.
"Good morning," the former British ambassador to Moscow then said cheerily to another pack of journalists as he strode through the VIP entrance of the council.
They were the only words he would speak in public all day.
A few hours later, Barrow would make history by handing the letter to European Council President Donald Tusk and formally beginning two years of tough negotiations in which he would play a key role.
This being a Wednesday in Brussels, his first stop was not history but a regular scheduled meeting with fellow EU ambassadors, for a debate on the effects of psychoactive drugs among other topics.
In the hallways of the EU council there were none of the tears and shock that marked the morning after the June 23 referendum when Britain chose to break away from the EU.
"Aren't you going to offer me your condolences? I'm British," said one EU official dressed in blue. The headlines on newspapers, scattered here and there, were the only other reminders of what was taking place.
Still in the Council HQ, Barrow eventually found his way to the eleventh floor of the giant egg-shaped building dubbed Tusk Tower, where its most senior occupant's office is located.
Holding the pearly white envelope, marked from "The Prime Minister" to "his excellency" Tusk, he entered the EU president's office, decorated on this occasion with Britain's Union Jack and the blue and yellow starred flag of the EU.
After about 30 seconds of chat, Barrow finally handed over the letter, which former Polish premier Tusk received with two hands. A few extra moments for the photographers and Barrow was gone. Mission accomplished.
Later, Tusk would add a touch of emotion to the day. "We already miss you," he said to Britain, after waving the six-page letter in the air at a short press conference.
A stone's throw away victorious Brexiteers swigged beers and ate cake at the Old Hack, the Brussels pub favoured by Nigel Farage, that sits in the shadow of the commission's Berlaymont headquarters.
Across the road EU flags flapped in the chilly March wind.
"It's a great day," said UK Independence Party MEP David Coburn as colleagues cut into an "Article 50" cake -- referring to Britain's desire to "have its cake and eat it" in the negotiations -- and poured out Cava, a Spanish sparkling wine.
"I hope our revolution or the 'British disease' as they called it, spreads across Europe."
"It's a start of a long journey. Hopefully we lead the way for the rest of Europe," said his MEP colleague Raymond Finch, a row of toppled dominoes arrayed symbolically on the pub table.