Odd gear change problem

You have to double de-clutch to select a lower gear on the move on a box without synchromesh. But this technique wasn't required when I took my driving test some years earlier than you, and synchromesh first gears were virtually unknown. Most cars with 'crash' first gears were happy starting from rest in second - first only really needed for hills or with a heavy load, so rarely if ever needed on the move. The advent of motorways meant the overall gearing had to be raised - otherwise engines would blow up with sustained high speed cruising, so first then became a gear which was needed on the move. And synchromesh became the standard. Then 5 speed boxes.

IIRC, the first mass produced UK made car with 4 speed box and synchromesh on first was a direct relation of your Anglia - the MkI Cortina. The first

Some older cars had three speed all synchro boxes but these were often four speeds with first 'blanked' off.

Your examiner may have been right to the letter of the regs on correct use of the gears, but most would have made allowances for an older car.