Evolving distributed systems are made of several physical devices distributed through a network and a set of functionalities or ap-plications hosted by the physical devices. The configuration of the phys-ical components may be modified through the time, hence the continu-ous evolving of the whole system. This should affect neither the hosted software components nor the global functionning of the whole system. The components of the systems are software components or physical components but their abstract models are considered with the aim of modelling and reasoning. We show that an event-based approach can be benefically used to model and verify this kind of evolving control sys-tems. The proposed approach is first presented, then the CCTV case study is introduced and modelled. The resulting model is structured as a B abstract machine. The functional properties of the case study are captured, modelled and proved. The refinement technique of Event-B is used to introduce and prove some properties.