Four is the loneliest number.
A veteran U.K. firefighter recalls the days of the 15-meter wheeled-escape ladder, predecessor to today's 13.5-meter extension ladder:
"It takes a crew of 4 to pitch the 135, where as the escape could (if the adrenaline was pumping) be slipped and pitched by one person, a crew of 2 was an easy job, and crews of 3 and 4 was luxury.
"Number 4 then had to hang on the escape to test if it was secure.
"Number 4 was also the person who had to run along the lengths of hose to make sure they were not kinked, run out the hydrant and before we had hand held radios, convey all the orders by running from number 1 to the pump operator (number 2) and then run back to repeat the order to ensure it was correct.
"The number always 3 stayed with number 1 at the branch.