BBC News - Sir Terry Pratchett, renowned fantasy author, dies aged 66
He was first diagnosed with Alzheimer's in 2007, but continued writing, completing his final book last summer.
The author died at home "with his cat sleeping on his bed, surrounded by his family," Mr Finlay said.
"In over 70 books, Terry enriched the planet like few before him," he added.
"As all who read him know, Discworld was his vehicle to satirize this world: He did so brilliantly, with great skill, enormous humour and constant invention.