Process of elimination: if they dismount, they are technically Dragoons, if they fight from their steam carriages then they are Steam Heavy Cavalry; Obviously NOT Lancers, maybe Hussars ?
Officially: "Princess Beatrice's Own Experimental Mechanised Steam Hussars"
Unofficially: "Beatrice's Boilers"
Just an idea
PS Joe is Annie Norman in UK going to be stocking these? My original hoard from the kickstarter is unpainted yet but not forgotten!