The Chosen One has landed and don't we know it, dropping by for a cup of tea and chat with the Queen, while Europe’s leaders give him the cold shoulder and voters here are preparing to give Brown the boot.
London's locked down as the Likely Lads polish their egos in a money wasting charade, amid unprecedented hype and security.
The Popular One is packing a weighty agenda as well his teleprompter, on his first journey across the Pond since the American public were duped into staking all their hopes and dreams on a slick snake-oil salesman from the Windy City.
For the White House, both China and Russia are the key reasons for the London stop-over and a quickie show-case summit is neither the time nor the place to look for magic economic solutions.
Meeting Her Maj is a chance to go global with media coverage. But there will be no time for spin or a teleprompter at that meeting. Anxious about the state of the economy and her people's dire future, the Queen has already been briefed by her King.
There'll be no manufactured and manipulated mass adulation for the Superstar this time. This is the real world. Something which the president is finding hard to come to grips with.
In London, all police leave is cancelled, hospitals on stand-by, drains and sewers checked for pesky protestors in a £7 million lock-down. The Beloved One brings with him two aircraft, two helicopters, two bulletproof road-beasts and a 500-strong army of special agents and advisors. And a present for the Queen. And a teleprompter. And for what?
G20 has dwindled to G2. He stands alone with his new Brown poodle and a painful fiscal stimulus, with France's Sarkozy threatening a walk-out and Germany's Merkel giving a resounding Nein.
Obama's rapid-fire tour comes with a Depression begging bowl. Brother can you spare a dime? More help in Afghanistan? A co-ordinated fiscal stimulus? Sorry, we're out of cash. And troops.
Desperate but divided on ways to lift their countries from economic misery, the London summit was doomed before it started, overshadowed by a US-European row about how to respond to the economic crisis.
Europeans want institutional reform. The Deluded Ones want a fiscal stimulus, with trillions of dollars of borrowed money on borrowed time threatening to bankrupt their economies.
The two students of Keynesian economics prefer to concentrate on the Master's borrow and spend economic science solution for a recession, neatly skimming over the first half, where Keynes was adamant that only came after squirrelling away cash during the boom years for that inevitable rainy day.
Setting just the right tone for the EU-US summit in Prague at the weekend, deposed Czech prime minister Mirek Topolanek, helpfully warned that US economic policy has put the country on the “road to hell”.
Away from the love-in, Obama and his Brown have split Europe, wanting to borrow and spend their way out of a recession depression. Europe wants to concentrate on regulation and controls which would not go down well with Brown's banking buddies. China, which holds the purse strings, may lend to dodgy countries but only if you ask them very nicely.
For Obama, wearing his Bush neocon hat, it's off to meet Nato chiefs to bully them into sending more troops to kill more muslims in his Vietnam war in Afghanistan, with a dangerous expansion inside Pakistan. Then swapping for a pseudo-liberal hat, swinging over to reach out to muslims in Istanbul. Crazy guy, crazy policies.
Fresh from his sermon on the mount at St Paul's and staking everything on a vanity save the world summit, no doubt G20 minus 18 will be spun as an amazingly wonderful success for the Supreme Leader.
But with his eye on the chance and knowing which side his bread is buttered, Obama has found time to squeeze in a meeting with Cameron, waiting in the prime ministerial wings.
Any real breakthrough, particulary a much hoped for thaw with Russia, will happen behind closed doors. A skilfully worded and totally meaningless communiqué will be issued but there'll be no big deal about a New Deal. One of the few things world leaders are likely to agree on is that Brown's borrowing plan is not the answer.
Deluded Brown has staked his political future on the G for Gordon summit and the endorsement of the Popular One. But the president has four years of wriggle room left.
When the dust settles, love-struck Brown will be left alone in the world with egg on his face, with only his Downing Street photograph album and a boxed set of unplayable DVDs. And taxpayers will be left with up to a £50 million bill.