With thanks to Sonya Taaffe for pointing this out:
Meryvn Peake's widow, the artist and writer Maeve Gilmore wrote a fourth Gormenghast novel-- by hand in exercise books-- which her granddaughter recently found in the attic of the family house in London.
Gilmore based the novel-- entitled Titus Awakes-- on a short note her husband gave her when Parkinson's Disease made it too difficult for him to pursue Gormenghast further.
Their son is negotiating with publishers.
Very timely as 2011 marks the centennial of Peake's birth.
For more, read this and this.