The werewolf claims it wants to infect Queen Victoria, and through her gain control of Britain and the Empire she commands.
That’s not entirely true. It’s what the people controlling it want, but in truth, the werewolf is as trapped on earth, where it doesn’t belong, as the Queen is trapped within Torchwood House. All it really wants is to be freed so it can return home.
The Doctor has the means to make that happen, he just needs to refract the moon’s rays at exactly the right strength and frequency, bathing the werewolf in its light, and…