It was Conservative David Cameron who made the first move. He had watched Lib Dem boss Nick Clegg for some time and was fascinated by what he saw.
Here was a man only three months his junior. He had the poise and charm that is instilled by a good fee-paying public school, he moved in the same high social circles, he wanted to see more choice and competition in public services.
He, too, was a thoroughly modern dad and he played tennis.
They certainly had a lot in common. Now they both led a political party: dash it all, why didn't they get together sometime and have lunch?
An invitation was sent to Mr Clegg shortly after his elevation to lead the Liberal Democrats in December 2007.
Mr Clegg rebuffed it, saying he did not think such a meeting would be appropriate.
Half a parliamentary term separates that first political flirtation from the matrimonial negotiations of the past three days. Things have been said, cross words have been exchanged, they clearly have their differences. Yet they still have an awful lot in common.
Both are the descendants of aristocrats: Mr Cameron's line runs to an illegitimate daughter of William IV, Mr Clegg's to a Russian baroness. Their fathers both worked in the City of London while their mothers were in public service -- Mr Clegg's mother taught disabled children, Mr Cameron's mother was a magistrate.
Both were sent to preparatory schools. Mr Clegg had been a pupil at Caldicott a few years ahead of George Osborne and had gone on to Westminster. One fellow pupil, Alex Michaelis, would grow up to be an architect and draw up an "eco-makeover" of Mr Cameron's West London home.
Both did a spot of acting while at school. Mr Clegg was brilliant, say teachers and contemporaries. Mr Cameron wasn't bad either, according to Christopher Black, a former school play director at Mr Cameron's old preparatory school, Heatherdown.
Both went on to have what Mr Cameron likes to describe as "a normal university experience" at Oxbridge, disdaining student politics in favour of tennis. Mr Clegg was allegedly a member of the Cambridge University Conservative Association, though if he joined, it was for the social events rather than the ideology.
The future Liberal Democrat leader spent longer in education and studied less conventional subjects -- against Mr Cameron's degree in politics, philosophy and economics, we must set his degree in anthropology and his master's thesis, composed in America, on the philosophy of the deep green movement.
Still, when he left education, like Mr Cameron, he moved into politics, helped by a family friend. Lord Carrington, the former Tory Foreign Secretary, recommended Mr Clegg to the Conservative EU Commissioner Leon Brittan. Mr Cameron's way to a job in Conservative Party headquarters was allegedly smoothed by a call from the Queen's equerry, a family friend. When they finally arrived in Westminster, two fresh young men with a plausible manner, their rise was swift.
Mr Clegg has pushed hardest against such comparisons, and against the idea that a common background entails a common point of view. In an interview last summer, he protested that their values were "completely different".
"You know, I didn't spend my life hovering around the Westminster village," he said. "I am a complete newcomer, I only arrived here in 2005. He [Cameron] was a party apparatchik, I think I did some basic PR stuff for a telly company, then was back in politics again. I worked as a journalist for a while, for two years I managed development aid projects in the former Soviet Union, I was a trade negotiator and the first time I did my time in politics wasn't even here, it was as an MEP."
All of this is true of course, from a certain point of view. From another, his path looks very similar. There was no Bullingdon Club, but he might just as well be classed a professional politician, trained in Brussels rather than Westminster.
His arrival as the rising star of the Liberal Democrats irritated members of Mr Cameron's team, who could not understand why he was not a Conservative. His opponent in the Lib Dem leadership race, Chris Huhne, made hay with the similarities between Mr Clegg and Mr Cameron, saying there was no gap in the market for a third party "parroting" Mr Cameron.
Mr Cameron's initial reaction was a charm offensive. When that was rebuffed he tried to ignore the new man -- he, too, seemed to recognise that there might not be room for two men of that mould in British politics. Asked for his favourite political joke, he replied: Nick Clegg.
Now that formal courtship is under way, their similarities may help the match. They are both affable, self-effacing, occasionally brittle when challenged. And they both play tennis.
Had they ever played tennis together? "I can't think of anything worse than going and doing that with people that you spend half your time shouting at," Mr Clegg said recently. It was a good answer -- it showed he had a life outside politics and a slight disdain for the its clubs and societies. Mr Cameron might have said the same firstname.lastname@example.org