By Robin Brant
BBC political correspondent
I'm sitting a few carriages down from Gordon Brown as I write this. I can't see him but I am sure he's smiling as we speed through Middle England. He's smiling because he's going home as prime minister.
Mr Brown was addressing a campaign event in Manchester
Just a few minutes before the train pulled out of Manchester Piccadilly it was confirmed that he now has the support of so many Labour MPs that the only other contender, John McDonnell, can't amass enough nominations to make it onto the ballot paper.
So, no contest. Gordon Brown will carry on touring, "listening and learning" as he keeps telling the crowds at the Labour events he's notching up day by day. But his will be the only name on the list to replace Tony Blair.
The omens from today are obvious now I look back. On the train up here about eight hours ago the chancellor sat a few seats away from me in standard class, ever the prudent money man.
'In the bag'
Now we are returning to London, the prime minister-in-waiting is up front in first, surrounded by his campaign team.
It won't be official until tomorrow when Labour close the door on nominations and it confirms that Gordon Brown is the only contender.
In fact it won't be "official official" until the Queen asks him to form a government in the last week of June. But it's in the bag now.
The Virgin West Coast Mainline has witnessed a little bit of history today
A few hours ago I stood and listened to him spell out his priorities for the future, for the third time in as many days.
Sitting in front of about 500 invited guests at a Co-operative Society event he was very comfortable.
One adviser within earshot whispered to a colleague: "He's really getting it now."
There were the customary gags about Olaf Palme and Richard Nixon.
He did relish the chance to explain his mission though.
He wants to see an "environmental corps" for young people to do work in Britain and abroad to help prevent further climate change.
He wants to "make the World Bank a bank for the environment".
Rather ironically, looking back now, he restated that he would welcome a contest for the Labour leadership after one questioner put it to him that an uncontested victory would be damaging to the party.
The chancellor also paid tribute to Tony Blair saying: "I think his brilliant achievement in the Northern Ireland peace process is yet to be fully recognised".
Funny how he didn't refer to him as prime minister in that moment.
Now we know that the man sitting a few carriages from me as we hurtle through the home counties is destined to carry that title, for definite.
The Virgin West Coast Mainline has witnessed a little bit of history today.
He got on the 1435 to Manchester as chancellor and now he'll step off the 2015 to London as prime minister in waiting.