Following on Andrew's comments on his experiences of mixing a bit of petrol, the pump could suffer suffer a little as the pump will have run for a time with a lack of lubrication. Good job it was a Bosch and not a Lucas. If a Lucas runs sans lube it really throws its toys and seizes up its distributor head, wrecking it beyond repair. The Bosch is an inferior pump to the Lucas in many ways but it is one tough old beast.
The K light came on because the pump lost control of the timing.
In the case of a serious lack of lubrication in the pump, two areas can wear; the timing actuator piston (which is PTFE coated) and the HP pumping element. Wear in either will cause a bit of hard start but wear in the latter will show up mainly as a real reluctance to restart when hot. Wear in the former tends to cause the K light to come on. So, in short, if you're starting OK from cold (ignore a puff of blue smoke, that's normal), the K light is always off and hot starts are no problem then you're OK.
In your case Andrew, I reckon your starting issues are not so much as the pump as some secondary damage that running on petrol may have caused. Damage to the combustion chambers and/or valves or rings through detonation (severe pinking) in a similar way that ether (easystart) will cause damage. It's just a theory of mine and I have no substantiating evidence whatsoever but your symptoms point to less than perfect compression and petrol-induced detonation could cause this.
