If you have a basic code reader, set it to read live data and check the coolant temperature looks about right with a cold and hot engine. If you can get the car where it won't start, crank it over on the key and read the engine RPM on your scanner- it should crank over between 100-300rpm. If there's no reading, it's probably an internal fault in the crankshaft position sensor (the sensor has a coil of wire inside which when cracked can easily make and break as its temperature changes). I'm not sure if the Morgan is the same, but on the Range Rover and X5 the sensor is located towards the bottom of the bellhousing and is easily accessed from underneath.
