The Fifth Door by Nigel Roth

In my hallway there are five doors, but only three actually open.
Two lead to reception rooms, the whimsical Wedgwood-blue drawing room, and the ample apple-green grand room.
The two that are permanently closed are only there because the architect who built my house was a typically-obsessive Georgian, and his principled mind dreamt in classical proportions and compulsive symmetry, and so he placed two additional faux doors in the hallway to enable him to get some sleep at night.
The fifth door which sounds like the first book in a Stephen King trilogy, is only one-hundred-and-twenty-seven millimeters high, but is an exact replica of the full-size ones, and is washed in the same sunlight yellow, with a gold handle.
I’ve often knelt low, in line with the burgundy skirting board into which this mysterious door has been placed and hung on tiny hinges, and marveled at how small children must've been two-hundred years ago.
I wonder if Kathleen Mary Norton did the same.
If she did, it was in The Cedars, in Bedfordshire, England.
The Cedars, like The Limes where I live, is also a Georgian townhouse, and Norton was raised there from 1903 when she was born, the very same year that my house became part of the nearby grammar school, as her house has now become.
Her childhood, we might imagine, was spent creating the adventures of Homily, Pod and Arrietty, who would've been perfectly able to use my diminutive door with ease.