I can vouch for this. I was sitting at a bar in Memphis, TN when the guy next to me said apologetically, "Sorry guys, I'm about to get a bit British". The waitress showed up with plates stacked with white bread, fries and mounds of butter. He built up a sandwich as described above and ate about three of them. The next day I went to work and described this peculiar behavior (behaviour) to a co-worker - also a Brit - who recognized it right away. "Oh, a chip buttie!"