The principle of not engaging first when moving comes from the days when I started driving and there was no synchromesh on 1st, but it was sometimes essential to change down when moving as many cars only had three speed boxes so if you were climbing a steep hill you would stop otherwise. Most of us perfected the art of 'double decluching' which matched the speed of the gears so they would engage without crunching. With modern synchromesh changing down into 1st is fine providing it is done at an appropriate speed.

In 1977 I was taught that first gear in manual cars should only ever be engaged when the vehicle is stationary. I have driven many cars and agree, in any event I cannot really conceive a situation where one would want, or need to.

30 years after that, when I started to learn, it was also the received wisdom. The synchromesh tells you that it doesn't want to do it!

I learnt in a Honda Jazz; it would set off in 2nd gear.

I use 1st to creep in, if the traffic situation calls for that.

They're also taught these days to sit at junctions in gear with the clutch depressed however long they are queuing, which won't do much for the clutch release bearing! We drummed this out of our children as soon as they had passed their tests.

Never put any car into first from second, you'll break something. If you try it it's obvious, only takes an ounce of mechanical sympathy to appreciate and never do it again.

If you really need to, like on a steep hill, a bit of double declutching will help, if you've got an engine where the ecu doesn't actively discourage it.

Unfortunately they do seem to encourage learners to do it, all part of the arcane art of the driving instructor.

Similarly, they encourage learners to wait at the lights with the car in first and the clutch depressed. Idiots.