Once I was happy, I stained the inner edges of both the window frame and corresponding holes in the door.
Next, I fixed the top length of batten and the frame for the glass.
I then fitted the glass into position with window putty, then the window frame. I carefully compressed the whole lot by moving around the area with clamps, spreading the pressure as evenly as I could.
Once I was happy that all was set in place, I removed the excess putty and cleaned the glass.