My friend's Swedish Police SWAT guys were training CQB with Mel Perry of SAS fame a decade ago and were shown SUL, but without the catchy name.
Mel said that it was used by the SAS in N.Ireland when running in public with drawn guns.
They were doing this in the 1970's.
As to the photo ( and is that Kevin Davis of Akron PD?) I would like to see the elbows held in closer to the body.