The car has been running fine of late (aside from a leaky airbox).
However just now, on my way to work, after 4 miles of typical mid-morning driving (bit start/stop and a few fast bits), whilst sitting at a set of traffic lights, the engine just cut out.
No splutters, no funny idling, just as if it had been turned off.
It wouldn't then fire up. Turns over fine, but just not catching.
Stuck the hazards on and prepared for the worst (was at the A1/A406 junction) and after 5 attempts at starting it, it fired up as if nothing had happened.
Every set of traffic lights therein was met with some trepidation.
Could this be the signs of a near-to-failing crank sensor?
There were no warning lights on the dash.
MAF was unplugged on this journey.
Yes, I think you're probably right. It does sound like what happens when a crank sensor fails. I had the same symptoms with a different car, plus sometimes the engine will run fine when stopped but won't restart an hour later, due to heat soak (an overall slight warming after switch-off). Actually in your case, the heat soak probably occurred during the slow traffic after the faster run.
At least it's a reasonably cheap part to replace as a precaution?
As you say, no splutters or idle problems, so not likely to be a fuel fault. Or ignition coil failure, as that would only affect one cylinder.
You mentioned there were no warning lights, so the CODE light had gone out. My CODE light was intermittently staying on and preventing starting, but I don't think a CODE fault can stop the engine once running (I've never heard of the CODE light coming on while driving).
"Every set of traffic lights therein was met with trepidation" - horrible feeling isn't it, driving a car that was hitherto reliable but is suddenly a liability... embarrassing!