Tom just showed up and corrected himself: geckos are the only *lizards* with vocal cords. Alligators and crocodiles, as well as various amphibians, also make noise. The article doesn’t say British are keeping crocodiles, although it might not be a bad idea, since they’re not allowed to defend themselves any other way. A Burmese python would deter intruders too, I’d think.
I know alligators (and crocs) make noise, but I don’t think they use vocal cords. On the other hand, they are the only reptiles with 4 chambered hearts (as if you care!)