Agapanthus

I'd never heard the common names for Agapanthus so I suppose it works both ways.
The Latin or botanical names of plants can be identified world wide whereas the common names differ from country to country as you said @PeterS.

 

I have bressingham blue which is deciduous, and evergreens in africanuus, black pantha and another which I can't remember the name of (£1 from the range) which is a very pale blue.
All of mine are in pots which I put in the greenhouse in winter.