I don't think it's a bromeliad, it looks more like a succulent to me. Check the flowers closely if it flowers and if it's a bromeliad the individual blooms (not the bracts) will have just three petals. I don't know how many petals there are on a succulent, but I know there are more than three.

Puya berteroniana (individual bloom)

I posted this on the cacti & succulents board and light was shed on the mystery. It's a Greenovia - rare and unusual succulent from the Canary Island. Thank you for taking the time to reply ☺

Hi Rachel - when we ask questions we all learn, so thanks for asking.

All the best, Nev