Commissioned from the ranks.
<<Across the military, a third of Army officers, a quarter of RAF officers and a fifth of Royal Navy officers have been commissioned having not joined at that level.>>
A little higher than I thought it may have been. Unsure, so I stand by to be corrected, but it probably saves a little money too I guess.
http://www.forces.net/news/hard-work-paying-lower-ranks-army#.WMj4lUoWfY8.twitter