what's the size of your unit?

As a science writer, I'm always looking for analogies, comparisons, metaphors to make understandable the vast distances or ridiculous tininess of things scientists manipulate and talk about. I thought about comparing a huge particle detector here, 45 meters long and 25 high, with a football pitch. (I'd already used the Olympic swimming pool, 50 meters, in another article.)

But I wasn't sure how long a football pitch is. A hundred meters? I googled it and found this letter to the Independent (UK) arguing against using the football pitch and such units to explain things.

Do your writers have trouble grasping such well-known and well-defined units as hectares and metres? Or do they just want to patronise their readers by implying that we might?...

Transatlantic readers will naturally assume you mean (American) football, which is played on a pitch 120 yards by 160 feet. Australians may think you mean footie, which is played without apparent rules, on an oval of ill-defined size. And to armchair fans, myself included, a football pitch is just a green rectangle on the TV screen, of perhaps 18 inches by 12. Until, of course, I upgrade to wide-screen.