Hey DW, I would talk with your HD to get an idea of Cart specs and food restrictions. 4-1…6-1…8-1….10-1 are all the amount of dogs to the  pound. 4 to a lb, 6 to a lb and so on. I think a good size dog, is a Nathans 8-1, if people in England aren’t used to large dogs they may give this a try. Nations is a good well know brand
                        The Royal Visit: June 7-12th, 1939, Franklin D. Roosevelt Presidental Library and Museum
 in 1939 [/size]second President of the United States, and his wife, Eleanor (1884-1962), wanting to introduce something truly American to the visiting King George VI (1895-1952) of England and his queen, served the royal guests Nathan’s hot dogs at a picnic at their estate in Hyde Park, New York on June 11, 1939. The press made a great deal about the hotdogs, and the picnic menu made the front page of the New York Times:[/size][/font] MENU FOR PICNIC AT HYDE PARK
Sunday, June 11, 1939
Virginia Ham
Hot Dogs (if weather permits)
Smoked Turkey
Cranberry Jelly
Green Salad
Rolls
Strawberry Shortcake
Coffee, Beer, Soft Drinks
[/size] The King was so pleased with “this delightful hot-dog sandwich” that he asked Mrs. Roosevelt for another one.
Much fuss had been made in advance of this picnic. Almost a month before the King and Queen of England ate their first hot dogs, Eleanor Roosevelt expressed concern about the upcoming event in her newspaper column called “My Day,” dated May 25, 1939 (a syndicated newspaper column published from 1935 to 1962):

Oh dear, oh dear, so many people are worried that the ‘dignity of our country will be imperiled by inviting Royalty to a picnic, particularly a hot dog picnic! My mother-in-law has sent me a letter which begs that she control me in some way. In order to spare my feelings, she has written on the back a little message: “Only one of many such.” She did not know, poor darling, that I have “many such” right here in Washington. Let me assure you, dear readers, that if it is hot there will be no hot dogs, and even if it is cool there will be plenty of other food, and the elder members of the family and the more important guests will be served with due formality.

It looks like the King and Queen were also worried about the weather. GGGEEEZZZZZZ they had a bit more help than you will, you think they could have bought a tent.

I would stick with the NEW York City hot dog idea, keep it simple, keep it good, the doggers in NYC do it good and keep it simple……..Good Luck……………Billyb