It grows well in a sunny spot - Devon. Has soft stems that have white liquid in when cut. We’d like to plant more of it.
This would be Euphorbia characias.
There are many, many species. Most of them have similar, to exact same care. This article will go over the care of Euphorbias:
https://www.gardeningknowhow.com/ornamental/cacti-succulents/euphorbia/growing-euphorbia-plants.htm
One branch is too tall. I hope to cut it shorter and get new branches on this one.
This article tells you how to prune and propagate Crown of Thorns plant. It has toxic sap, so be sure to wear gloves when working with it.
https://hort.extension.wisc.edu/articles/crown-of-thorns-euphorbia-milii/