A tip from France...
These are not made the same as British Breadcrumbs, as I live in France I use French Bread. Which, by the way, doesn’t go mouldy as British bread does so it's quite safe to leave old off-cuts or ends of baguettes to dry for a week or two.
When totally dry, cover the bread with a tea towel and bash it with a rolling pin until it's chunky. (A good therapy on a bad day!).
At this point save some of the larger bits to use as croutons, ideal for adding to Salads in the summer or Soups in the winter.
Then simply blitz the rest in a food processor to crumbs, as fine as you need.
Store in an airtight container until required.