Glad I found other people with this problem. It suddenly happened to me too.
I had the clutch changed and it's been since then. I'll be steering round a corner with the steering as tight as expected, or tighter like it's tramlining a bit, and then suddenly it'll go very loose as if I've lost the front end. Every time it happens it scares me because I think I've hit a patch of oil or something, but if I steer more I haven't lost it, it carries on around the corner.
The tyres are crap anyway so I'll be changing them but as it suddenly came on I don't reckon it'll be from that. I'll have a look at the bushes at the weekend if that's what others turned out to be.