We are a Nominet Member and Registrar (using the ZZHOSTING tag) and we use Nominet to register all domains with a .uk TLD, all other domains are registered using OpenSRS (Tucows).
As well as the registration terms of Unlimited Web Hosting UK Limited (t/a "zzHosting"), domains are subject to the registration terms and conditions of the relevant registry and which may change from time to time.