Having baked beans for breakfast is a distinctly British thing. Americans (and conservative older Britons) are always complaining about it. Yet Americans add syrup to bacon, which shows that breakfast habits are a matter of acquired taste.
The addition of beans to the full English breakfast seems to have occurred round about the same time that Heinz launched a famous 1967 TV advertising campaign ("Beanz Meanz Heinz"). Traditional English breakfast recipes before the 1960s include stuff like tomatoes (and kippers!) but not beans.
Heinz is an American company, but oddly enough its famous Baked Beans originated in the UK, where they are today regarded as part of the national culture. They are different from American beans, as the UK beans are mushier and less sweet.
Heinz was one of several American consumer goods companies that expanded into Britain in the 1920s, along with the likes of Kellogs, Hoover and other household names today. The first Heinz baked beans factory was opened in Britain in 1928. Baked beans were already a widespread and popular snack food by the 1950s. A second, even bigger factory was opened in Wigan in 1959.
Heinz supposedly launched its 1960s ad campaign after research showed that 1,750,000 British housewives bought Heinz baked beans everyday. So presumably plenty of people must already have been scoffing beans with breakfast by then.
But beans with a full English breakfast only seems to have become standard after the 1960s ad campaign, which is today acknowledged as one of the most successful advertising campaigns in history (In 2000 the slogan "Beanz Meanz Heinz" was voted the best ad slogan ever in the UK). One of the ads featured the following jingle:
You can't have stew for breakfast.
You can't have porridge for tea.
But we have Heinz beans at any time.
My brother John and me.
http://www.rachellaudan.com/2008/08/beyond-baked-beans.html
http://www.rachellaudan.com/2008/11/the-english-breakfast-then-not-now.html
http://www.roadfood.com/Forums/tm.aspx?m=400296&mpage=
http://www.responsesource.com/releases/rel_display.php?relid=19025
http://www.hjheinz.ie/products/heinz_baked_beanz.aspx
http://www.hatads.org.uk/hat/newsitem.php?A=104&C=21