Maybe it was their amswer to tricking the bolt into staying in place as you creep up on it with a washer and a nut. The head of the bolt will hit the far end of the small trough in the starter body. Or its long enough to hold the thread with your middle finger while loading the nut or washer on with index finger and thumb. My usual solution is to chop up a bit of fuel hose cut in half lengthways and put it in the trough in front of the shorter style bolt's head to stop the bolt just pushing forwards.
Having had plenty practice, I carefully slip the washer on then put one finger on the edge of the washer and press down to trap the bolt then start the nut with another finger and thumb. Easy.
and the best part of this is that I'm left handed.... If I drop the nut or the washer (my right handed use is okay but not infallible) will they just drop out on the driveway or will I cause catastrophic damage likely to knock the earth off its usual rotation and implode the entire universe?
A mechanic has to develop ambidexterity. I have no feeling in the tip of my right forefinger after cutting through the nerve, I just had to learn to use the next one along for fiddly things.
The washer will sit on the tin in a place where you need two fingers to get it back because your thumb won't reach. Magnet is a good idea. You'll need to dive right into the engine bay so your elbow is as far in as the tank panel for this job. Commit or face frustration. I'm just hoping some gorilla hasn't lent on the spanner for you, it's harder lifting to undo it.
I have one of those extendible magnetic probe things... you may guess I drop stuff in awkward places quite a bit
The downside is it'll stick to the tinware. lol Dropping stuff/tools into the marina is the sport here, most of us have a "sea searcher" magnet. People even fit steel covers on their phones in advance though... I got my wheel barrow back once but it took 5 magnets and and boat hook when Graham dropped his rudder in! One funny thing seen over and over is smug types with cork float keyrings but so many keys they still sink - but so slowly they also drift off to who knows where - no float and they go straight down.
Well I'm sorry to say that I've wasted all your time. Match abandoned. The nut on the D bolt has been done up by someone stronger than I. I have knackered shoulders anyway, and I can't injure them any further Sorry chaps. That's it.
I don’t want to encourage you to knacker your shoulder further, but if you put the ring end of a combination spanner on the nut, you can then hook the ring end of another spanner into the open end of the first spanner, giving you double the leverage, which makes even the tightest nut, relatively easy to undo… Or just ply someone bigger with tea and biscuits