I remember watching the cornetto trilogy ( https://en.wikipedia.org/wiki/Three_Flavours_Cornetto ) and always wondering why on earth they fill up the glasses up to the brim. It is uncomfortable to transport this way and not spill beer.

When CAMRA was new in the early 1970s, they started a campaign for oversize glasses holding a pint to the line instead of a pint to the rim, so that there would be space for a pint of liquid and a head in the glass. The big breweries hated this idea and mounted a reactionary campaign arguing things like it would be too expensive to replace all the glasses, or serve customers the full measure they had paid for. (My father was a new recruit at Guinness and sadly one of his early tasks was the pint-to-brim campaign.)

First sip's at the bar; then you can