This weekend marked the end of an era for the Liberal Democrats, as they move out of their headquarters at 4 Cowley Street for modern offices in Great George Street. I'm sure the thought of Cowley Street will evoke as many memories for other party staffers as it does for me - the small, bright offices full of newspapers and coffee; the balcony outside the press office which most of the building seemed to use for cigarette breaks (huddled under an umbrella in the rain); the constantly broken lifts, photocopiers, and IT equipment; the occasional stampede to the kitchen when the Campaigns department (who always provided good cake) celebrated a birthday; and the comforting knowledge that the Marquis of Granby was only minutes away at the end of a long week.
However, the offices, which you could kindly describe as quirky, weren't suitable for a modern political party. Campaigns sat two floors away from Press. The Policy unit was in an entirely different building. The photocopier was always broken. Moving out of Cowley Street isn't a time to for mawkish sentimentality. It's time to sit up and notice a party that is growing up - not just organisationally but politically.
For years no one paid attention to the Lib Dems. Universally thought of as inoffensive, policies that were generally ignored by the public became unrealistic or incoherent. At one party conference back in 2003, a serious debate was held on the rights of goldfish. Beards. Sandals. Porn for teenagers. To say the party lacked credibility would, to put it bluntly, be kind.
But the Liberal Democrats have been changing, not just since the election but since a new generation of politicians - Clegg, Laws, Cable, Huhne, Davey, Kramer, Browne, Teather, Swinson and numerous others - came to the fore. Politicians who were ambitious for the party and for liberalism, and wanted to turn the Lib Dems from a party of protest and opposition into something serious: a party that could potentially govern the country.
This is a movement that has been happening quietly behind the scenes for years. Chris Fox made the first steps towards ambitiously modernising the way Cowley Street operated well before the election. And the attitude and tenor of Nick Clegg's leadership made coalition possible in a way that it may not have been for the party in previous more tribal days.
The Liberal Democrats are growing up in public, but for the party this process didn't start on May 6 2010. Nick's challenge is to take the party with him through this process and make them a serious proposition as a party of Government at the next election in a way that it has never been before.
That primarily means being trusted on the economy - something the Lib Dems have never been close to before - not even when Vincemania was at its peak. If he can do that, the party can go into the election not as a wasted vote or a luxury vote or a protest vote, but as a party that can appeal to the huge section of the electorate who want to vote for someone more economically credible than Labour and fairer, more compassionate and more progressive than the Tories. It's about ambition for the party, not reliance on and descent back into their comfort zone - and it's very risky and very brave.