Sir Emyr Jones Parry is Britain's ambassador to the United Nations, a man at the centre of decisions which can make peace and war.
He has held the job since 2003 and is due to retire next month. The BBC's UN correspondent Laura Trevelyan spends a day with him.
"Premium economy?" asks Sir Emyr Jones Parry peering at an entry in the monthly travel bill for the UK mission.
Sir Emyr Jones Parry's days are long and intense
"Not club class," Mike Balmer, the head of management, assures him.
It is 0745 and Sir Emyr Jones Parry is carrying out one of his less high-profile duties - going through the accounts.
Not only is he at the centre of ongoing negotiations on getting peacekeepers into Darfur, but he is also, in foreign office jargon, the "sub-accounting officer".
It all adds up to a 16-hour day.
The ambassador's morning begins at 0700 when he reads through the diplomatic telegrams, which include instructions from London, and situation reports from the world's hotspots.
This particular day, Darfur, and the upcoming meeting of the Middle East quartet at which Tony Blair debuts as an envoy, are featuring heavily.
Sir Emyr is to introduce a revised draft of a resolution authorising the deployment of a joint African Union/UN peacekeeping force in Darfur to the Security Council later in the morning.
The initial draft was opposed by some members of the Council - and the Sudanese government - because it threatened sanctions if Khartoum did not allow the peacekeepers in.
This latest text has been "modified" - as diplomats like to refer to watering down - so it is more conciliatory, as the ambassador later tells reporters.
At just after 0800, Karen Pierce, the number two at the UK mission, Paul Johnston, the political counsellor, and Justin McKenzie Smith, the first secretary, join Sir Emyr to discuss the day ahead.
The four mull over possible names for the leader of the European Union effort on Kosovo.
The factors affecting the timing of a vote on the Darfur resolution are weighed up.
Are the South Africans on board for the Darfur resolution? Sir Emyr's assistant gets South African Ambassador Dumisani Kumalu on the phone.
It seems he is broadly supportive.
Then it is off to a European Union meeting, where the ambassadors from the 27 EU countries at the UN meet to discuss what is coming up.
That ends with a round of applause for Sir Emyr and his French counterpart, Jean-Marc de la Sabliere, both of whom are retiring soon.
Next, a brisk walk to UN headquarters, where the Security Council is about to meet.
Darfur will be discussed a situation that the ambassador has first-hand knowledge of after visiting the refugee camps in Sudan and neighbouring Chad in 2006.
"We were always very determined to try and bring peace to Darfur. Actually going to the camps is a humbling experience - actually seeing people line up, applauding, hoping, expecting.
Britain helped choose the new UN Secretary General, Ban Ki-moon
"In terms of what we have not done for the people of Chad, which is to provide them with real security, I'm very disappointed with that. Twelve months on we're still working very hard on that."
I ask whether the extraordinarily slow progress on getting peacekeepers into Darfur, four years after the killings began, is frustrating.
"The UN can be frustrating, period," comes the reply.
"Some people describe it as wading through treacle. But the challenge in the UN is to try and analyse what needs to be done in a certain situation.
"To then mobilise people to reach agreement, and then when you've got agreement, ensure that implementation happens."
This, he acknowledges, can seem like a never-ending process.
Whatever the frustrations though, the ambassador is a firm supporter of the UN, describing it as "remarkably effective" in dealing with global problems.
Although, he adds, "within New York, trying to get reform, trying to shake up the UN structures to make them more appropriate for the 21st Century, that's very difficult."
Inside the Security Council, the revised Darfur resolution is introduced.
Outside, the Sudanese Ambassador to the UN, Abdelmahmoud Abdalhaleen, tells reporters the text is "awful", and warns that Khartoum will say "no" unless changes are made.
The Sudanese have a problem with the mandate of the 24,000 AU-UN peacekeeping force to be deployed.
Sir Emyr goes from the council to a farewell lunch in his honour, being given by Caricom, the economic grouping of Caribbean countries.
After the Caesar salad, the crab cakes and the tribute, there are more meetings.
Then comes a lengthy encounter with the Sudanese ambassador - an hour and a half.
"He's calmed down a lot," says Sir Emyr afterwards.
'Making a difference'
That finishes just 20 minutes before the ambassador is due to be on parade for the garden party he is hosting to mark his departure.
The UN Secretary General Ban Ki-moon is present. Britain, as a permanent member of the Security Council, helped select him.
So how does the retiring ambassador view the world's chief diplomat?
"In terms of the way he's settled into the job, the position he's taken on key issues like the Middle East, climate change, Darfur, I can't fault him at all.
"I think he's adjusting to the difficulty of getting things through the UN system. And that is an art form."
The day is drawing to a close. A telegram must be sent to London, containing the developments on Darfur.
Sir Emyr Jones Parry is about to leave this world behind when he retires in a few weeks.
What is the worst part of this job? I ask him.
"Having an idea of what needs to be done and having difficulty getting agreement."
And the best part?
"Knowing something you've done will make a difference to people's lives."