[Rob Abbott]

The 37 pattern webbing was primarily designed in line with trials in the 30's as the British army modernised and adapted to new equipment and weaponry. The Battledress suit was pretty revolutionary at the time and the new webbing design reflected the need for greater flexibility and to cater for the new section LMG - The Bren
One of the webbing sets drawbacks was that it tended to pull the waist belt up at the front when worn with the small pack and the cross straps didn't produce an even distribution of weight. Hence numerous modifications culminating in the 44 pattern design which was not generally issued, being primarily designed for tropical use (although used in Korea)

However the 37 pattern was actually quite adaptable. Due to its modular approach it could be assembled in numerous forms and additional items added or left out. Troops could fight light if needed and the various formats made to fit the requirements of various roles - infantry- Artillery - Transport - etc

The entrenching tool was never adequate for the type of digging in required by the Infantry. The section therefore carried a mix of picks and GS shovels to do the job. A common version of carrying position of the GS Shovel was tucked in the belt so that the head covered The lower abdomen and Liver area. There was some belief that The shovel head would provide some protection against low velocity fragments.

The Assault Jerkin was a great piece of load bearing kit, enabling troops to increase carrying capacity and had superior weight distribution characteristics. However it's key drawback was the inability to fight light - it was an all of nothing type of garment. Its pobably why the units issued with the jerkin almost completely reverted to standard webbing once the assault phase was over

If anything the modern day PLCE type equipment is a direct descendant of the good old 37 pattern kit.
Again a mix of my own opinion and historic record.