I was a member of the Labour Party back in the 80s and early 90s, but, as Tommy Sheridan put it, I didn't leave the Labour Party, they left me.
I've c&b-ed quite a few times, Green a few times. I've never actually joined the party, but have thought about it.
I voted tactically for the Liberals in the 2010 election, thinking a hung parliament would usher in a new grown-up, consensus based politics, then watched in horror as they became partners with Trish and Co in the horrors that ensued.
I'll never do that again, and, as fervently as I want an independent Scotland, I'll never vote SNP.
They voted with Thatcher in the no confidence vote in 79. Any party whose opportunism brings about behaviour like that can poke it.