Should be impossible

For many years a daughter always bought me a Terry Pratchett book for Christmas or birthday, he wrote 40+ so there was no shortage. Then he died and she had to think of something else to buy me. She has not yet discovered the spin off publications, such as Wit and Wisdom of Discworld, the Science of Discworld, the World of Poo and Nanny Ogg's Cookbook.
I read that after his death he asked that all his unpublished work be destroyed and a steamroller was used to run over his hard drive, pretty effective.
It was a great surprise when I opened my Christmas present and found this. These are stories originally published in a paper under a different name so they are not really new.
The stories are not as good as the Discworld ones but its a delight reading new Pratchett stuff.