Browsing through the baking books on Kindle last night and I came across “Baking Real Sourdough Bread” by Dragan Matijevic & Penny Williams. I don’t need another bread book but at under £2.00 it had to be worth looking at. On first skim it looks like a pretty good sourdough introduction but (you knew I was going to say “but”) “These recipes include a tiny percentage of baker’s quick yeast. This is not essential to sourdough production , but it helps give more consistent and controlled results, which particularly useful for beginners. Purists may prefer to omit this!”
I know I’m a mad, fanatic, out-of-control purist and old and grumpy to boot (at least that’s what my Mom says), but aren’t there some basics that define sourdough?
The PArtisan Baker 
I agree you’d think so, and unofficially I’d say actually there are certain aspects… however officially its simply a free-for-all, wild-west territory, anything goes maelstrom.
Marcus – you’re worse than I am!
I like wild results – you never know what will turn up (ref. boules)
I suppose it depends on why one’s using sourdough. In my case it’s mainly for the taste so occasionally, if I’m in a hurry, I’ll add some commercial yeast to speed the process up.
Well, Ms Possum, with sourdough no two loaves are exactly the same. But in my experience the results are consistent.I mean I might get the odd splurge, but no great shocks.
Mike, why the rush, there’s always tomorrow. And if you add commercial yeast, the end product is not sourdough.
I’m with you, Mick. There is no rush, and yes, it’s always edible. Maybe a bit better, or a bit not so perfect, BUT, always tastes Ok.