Hello,
Maybe the T 1-9 is a variant of the Gipsy Major Series 10 Mk.1 or Mk.2.
In "The De Havilland Gipsy Major Series 10 handbook" I have only :
Gipsy Major 10 Mark 1-1, 1-3, 1-7, 1-1A, 1-3A, 1-7A and Mark 2 and 2-1.
The Gipsy Major Mk.8 is the RAF version of the 10 Mk.2.