Where has Insert Image button on toolbar in 2.6.1 gone?

I’ve just upgraded from 2.5.1 to 2.6.1 and noticed that the insert image button on the toolbar – when trying to create or edit a post – has dissappeared. I don’t want to use the ‘add media’ route, I was quite happy with the ‘insert image’ option that allowed me to vary size and text associated with an image and was working perfectly until it vanished.

Can anyone tell me how to get it back please in 2.6.1? Thank you.

c0y0te