I called it back and the greeting wasn't at all clear (on purpose I guess) Sounds like Nexus UK on behalf of "irghehbgkbwlf" energy. Spam, Now blocked.
Got my first call from this number today but didn't answer as knew in my gut it would be a waste of my time. Have blocked the number now so they can try as much as they like as my phone won't ring. Lol