No, not the cover photo of my new novel RUC & IUDs , a gripping fast-paced tale of forbidden cross-denominational love in Northern Island.
It is, rather, evidence of research done a couple of months ago after I worked out there are very good reasons for serving beer in glasses way back here in May. Like any late convert, when a friend offered me the latest Guiness in a bottle, I demanded a glass. "No" he said, "it doesn't need one". He was right, so we smashed open the bottle top have a look at the widget inside, took a photo with his camera. The photo came a few weeks ago.
I'm going to be a bit a priori (read lazy) about this and offer the following explanation. The widget creates a tunnel in the flow to the mouth allow the flavour to breathe and open up, just as happens in a glass. I went on to imagine that the wings create a hydrodynamic effect like a turbine. But then considered the less exciting, but more important function of preventing the widget becoming lodged in the throat.