Next time you get into a classic British sports car, please promise not to grind. No one does it on purpose, but it sure seems like everyone does it a bit too often, based on the number of worn teeth you see in the gears on the table below. Everything you see is trash and went to the scrap pile for recycling because of bad habits by prior drivers.
If you are already a pro, you’ll find the video below an interesting study of what happens inside a gearbox when people are careless. And if you are still new to this universe, please watch the video so you can see what happens if you get sloppy.
You need to be at a stand-still to engage first gear with these non-synchro gearboxes. If you are moving at walking pace or faster, use second gear to start off, or come to a stop and patiently engage first. This way, your gearbox will last a good long time! The cluster gear above displays the worst case scenario!
There is nothing wrong with a non-synchro classic car gearbox. There is no reason to be afraid of them or to avoid them. But please treat them with respect.