David was misquoted when speaking about his role in the upcoming Harry Potter films:
"Yeah we're working on the last film, which will be split into two but I'm not really involved in it. I'm not in the last films much. It's a week's work here and there."
What he meant was that he did not have very significant roles in OotP or HBP. He hasn't even been given a script yet for DH, so he doesn't know how many scenes his character will have.
Source | Thewlis Rox
Isn't this exciting? I am keeping my fingers tightly crossed that he will have a much bigger role in the final 2 films, as I believe the Lupin/Tonks storyline is crucial in the final outcome of the series!!