I was there too and we had a chat.
While I was at the bar, a local sidled up to me, to set me straight: "It's a f---en Richmond pub, mate. The publican brings out a big cup when Richmond wins. It gets passed around. You have to have a drink. He won't let you go home. It's the only time he brings it out." Then he corrected himself. "Oh yeah, and for buck's parties."Yep, that was me.
Here's the link to the whole article. Read it and you'd swear you were there too.