Do you know what it is?

No, neither do I!
Got this plant several yeas ago as a small cutting from my sister who lives in a Essex. It's grown considerably and produces masses of these little white, waxy flowers but I've no idea what the plant is called.
Had a really lazy day today just pottering around the garden and doing not a lot. Now seated with a glass of wine and will likely have a refill once I've finished it!