(The Beatles, 1963)
It turns out there is a Ministerial Decree about letter boxes. Their height, size and position. And unfortunately, as we were politely informed by a recent note from the postman, our neat little brass letter box, which is part of the original door, is not the requisite 23 x 3 cm.
So we have rigged up an temporary alternative (which has the added benefit that it keeps the post out of the way of muddy boots tramping in and out the house).
In the longer term, we will need to find a way to add a letter box to the front door. Maybe at the same time as we give it its facelift, but that's another story.