You're about the limit, that's what you are, growled Whittington, with a sort of unwilling admiration.
Whittington admired her yet growled "You're about the limit, that's what you are". 
mnli hypothesis: Whittington admired her yet growled "You're about the limit, that's what you are".  premise: You're about the limit, that's what you are, growled Whittington, with a sort of unwilling admiration.