Main agent told me to get AA to fix or recover car. AA fixed it by bleeding clutch and topping up fluid.
Both of us were amazed that the minimum mark on the fluid container is actually below the top of the outlet to the clutch. The level had been about half way. Perhaps air entered as I was cornering, that's all I can think of, though main agent did not agree.
Several lessons learned:
1. Both brakes and clutch share the same fluid. The clutch fluid outlet is higher so the clutch will fail before the brakes if fluid level drops. This is a deliberate safety feature.
2. As pads wear, the fluid level drops so should be kept topped up to the maxi mark. On my very expensive service this was not done and I'd been intending to do so, but hadn't clocked it as an immediate priority.
3. To bleed the clutch, the battery and battery tray have to be removed to gain access. The outer of two spring clips has to be prized up/off, to open a valve in the pipe. Pedal is then pumped , the valve being closed each time the pedal hits the floor, until all air is dispelled. Fluid dispelled is caught in a receptacle, fluid level kept topped up during the process.
Main agent is not convinced that there isn't an underlying problem so want me to call in for a check up. I'll have to drive around a bit and see if the fluid level changes.