[alnitak]

The advanced math was obviously too much for the BBC editorial dept. Most journalists are still at the "some beans" stage of arithmetic. They even mixed up the units, moving from cm to feet with the sort of wanton abandon which would do NASA proud.

If we assume 4 cm PER DAY, we get 4x7x12 = 356cm, which is a lot closer to 12 feet.

[alnitak]

That's a typo. I really did mean 336 cm, honest.