I was one of those young-ish activist types who took part in the extremely unofficial talks held between the Young Liberals, Liberal Ecology Group and the Green Party in the late 1980s to see if there was any basis for a re-merger.
In practice, what actually happened was that the Green Party abandoned the talks in response to their spectacular result in the 1989 Euro-elections, and - as it turned out - the Liberal Party merged with the SDP.
That probably was all for the best. We have gone our separate ways as parties in the last decade and a half. Everyone would agree that there are parts of the Green Party which are emphatically not liberal. There are certainly parts of the Lib Dems which are not green.
But back in 1987 (or was it 1988?) there was a strong measure of agreement. The main difference, as it was put to me by a prominent Green activist, was that the Liberals were more pragmatic - they compromise on the way to their objectives.
I noted this remark away rather cynically. Just wait until they run a city, I said to myself, and we'll see how long that attitude lasts.
What I didn't understand at the time was that this division (the realo/fundi division) was absolutely at the heart of Green politics, as much as the Tories are divided between free marketeers and xenophobes or between social and economic Liberals. The division has emerged over and over again, and disastrously, from the Hungarian Green Party to the Green ruling group on Brighton and Hove Borough Council.
All of this is a way of saying I don't agree with Caroline Lucas, the Green MP, when she dismissed the idea of any kind of electoral arrangements between the two parties, as proposed by St Ives MP Andrew George. Because there are ways in which Greens and Liberals represent missing wings of each other's philosophy.
I like and respect Caroline. She is a principled humanitarian, and she is quite right that we shouldn't waste time with any kind of formal electoral pact. But I'm not sure we have the luxury of happily bashing each other when a combined Ukip/Tory force may emerge to take down the wind farms and frack us all to kingdom come.
She is quite right, it seems to me, that the Lib Dems in office have compromised too much with nuclear subsidies (I believed Chris Huhne's 2010 promise "read my lips, no nuclear subsidies" and I was horribly wrong).
But she knows as well - not just that the Green Party originally emerged from the Liberal Party, but there are important parallels between us, and that there are Lib Dems who would oppose nuclear energy or shale gas extraction all the way, just as she would.
It makes sense, it seems to me, to work together if we can do so informally, to keep them in Parliament and keep her in Parliament, and bring in some colleagues too.
So yes, I would back informal arrangements, starting in Brighton. A Liberal UK needs people like Caroline Lucas and a Green UK needs people like Andrew George. The barbarians are now at the gate, and we may look back in a few years and wish we had acted together when we could.