Was that the starter or the Mrs?... have you tried hitting it with a lump hammer and swearing at it a lot whilst waving the hammer around frantically?? not a word of a lie, that actually made my started work again!!
Sounds like the starter solenoid got jammed on and the motor was drawing current all the time. Hence the burning smell as the cables and the motor got hot. Noise would have come from the drive pinion being engaged with the flywheel and spinning the starter whilst the engine was running.
Sometimes they just do. It only takes a tiny piece of grit to get into the solenoid between the plunger and the coil and that will do it. You may find that a good clean of the starter will sort the problem so long as the brushes or slide rings have not burnt out.Seems to have been the case Shifty, recovery gave me a bump and she ran with no further issues but the starter's knackered so will swap it out for another tonight.
Any idea why it would jam on though?
Not if the engine was running as the full output of the alternator would be across the battery. I reckon you would have juice for long enough to burn the cables and the starter.Sounds like the drive pinion got stuck in the engaged position; if the solenoid stuck then your battery would have died within a couple of minutes or so!