One of those little snacky lunches that are a treat is grilled cheese on toast. For years I thought it was called a "Welsh Rabbit." However in my teens I found out it was in fact called a Welsh Rarebit, which helped clear up the confusion as to why welsh rabbits were so odd compared to the English type.
Now of course, if you want an upgrade to business class you can order a Buck Rarebit, which has a poached egg on top.
Now there is one other upgrade you can take straight into first class which is a Passfield Special. This culinary delicacy was served to me some fifty years ago in the Passfield Arms, near Aldershot - the home of the British army. It is a slice of buttered toast with a slice of ham, then grilled cheese, with a poached egg on top. Like lots of upgrades in life, it's tough going back to economy afterwards!