Their logic is easy to follow: there are no hybrid CVs available on the UK market, but companies like Smith Electric Vehicles of Tyne and Wear, were displaying a "new generation of battery-electrics comprising repowered versions of established diesel-engined models, notably Ford Transit vans and chassis-cabs at 3.5 tonnes gvw and the Avia chassis-cab (dubbed the Newton by SEV) at 7.5 and 9 tonnes." In the UK, hybrid CVs are in the prototype stage and the EVs are already on the streets (see, for example, this post).
One big push for these clean trucks is the planned Low Emission Zone (LEZ) restrictions in London. Smith Electric Vehicles use Zebra sodium nickel chloride batteries instead of lead-acid type batteries. Newspress learned that these power packs are about 80 percent lighter than lead-acid units with the same energy storage and deliver more performance.