Mr Tanner's mother sat at the front desk of her son's poky little office, knitting.
Well, of course she did. Knitting is one of the things mothers do. In her case, she was using 6mm high-tensile steel winch cable, and her drop-forged molybdenum needles were bent like saplings in the breeze as they took the five-hundred-kilo strain required to keep the line taut. It was going to be a babygrow for little Paul Azog.
Edited to add: The books in this series are, in order:
The portable door
In your dreams
Earth, air, fire and custard
You don't have to be evil to work here, but it helps
The better mousetrap
May contain traces of magic
Though there's no mention of J.W. Wells or any of that company's employees in it, I suspect that the standalone novel "Barking" is set in that universe.