Dinsmoore had a noted lack of enthusiasm for Lord Chumley's schemes, greeting his announcement he would hunt Optimus Prime with only a tired "oh dear." He tried to gently dissuade Chumley from continuing, suggesting they call in early because he was bushed.
He had a black sense of humor, noting that the Decepticons were "just like the Humane Society in a way" when they spoiled Chumley's hunt, and dryly suggesting that, though Prime's value as a trophy had been ruined, he could still be made into a nice coffee table. When Lord Chumley was contemplating how to destroy the Decepticon Triple Changers, Dinsmoore gleefully suggested molten lava.
When Prime breached Chumley's castle, Dinsmore hid in the tank in the trophy room, presumably evading capture, for a time at least.