It seems to me, having viewed numerous pix, that the Brit system of having one's pack supported by one's pouches worn on one's dorsal (back) side has some advantages.

Except for the question of:

1) Accessibility to such pouches.  Is wearing frequently used pouches on one's back a fundamentally good idea?  Looks like all the pouches are mag pouches.  Doubt if this is wise.

2) How is the pack supported by empty pouches?  Surely such pouches, whether they be mag pouches or other, will be emptied during a long patrol.  How do the emptied pouches support the pack?

Response in red.

You provide some plausible answers to my concerns.  I presume the packs worn using this set-up have belly-bands (as opposed to load-bearing waist belts) so the packs don't flop around?

Generally speaking in the military the comfort and stability of a waist belt is traded for the quick ditch possibility, usually they are unbuckled. Plce has a waist belt made of basic webbing with a slightly padded Cordura parts net the back, most of the aftermarket ones have nothing, even the most expensive ones like the jayjays one that's mounted on plastic DEI frame used in usmc packs.

I have somewhere a dragon supplies one that's like a Medium Alice pack and just like the issue patrol packs it has nothing.

A couple of images from a 2008 training in UK Belize Garrison (their jungle training center) showing how the Northern Ireland Patrol Pack (patrol pack, 30 litre dpm irr) is worn resting over the pouches.




As a side note, a tally counter taped to your rifle makes an excellent pace counter (still in use today, glued over the magazine well in their AR15 style diemaco rifles)

British Army TV uploaded this training video footage. You can see how load carrying is managed at a basic infantry level. Armor is worn with only the infrateam radio and hydration carrier (an admin pouch for squad leaders), the rest goes to the belt kit which makes for a quickly scalable kit. Patrol type pack is worn and rests over kidney pouches (Camelbak packs seem popular today), looks like there are some awkward loads like anti tank weapons and litters attached to them as  well.

Oh and apparently surplus plce pouches are still a viable option to attach to your Molle carrier if you are a soldier from a budget minded nation (Greek soldier from OYK, which are Navy Seals counterpart).

Not strictly a surplus item, but a cool item in my opinion.
Surplus south african pattern 83 vests (and in a smaller quantity chest rigs) were very popular among brits, expecially paratroopers;
Karrimor, which is an outdoor and military brand famous in the UK made a copy of the rig.
It has been improved with mesh bottom on the pockets, fastex closures on the canteen hip pouches, back panel has been totally changed with a camelbak holder plus molle webbing and zips to attach PLCE bergen side pouch (they make also aftermarket ones configured with smaller pouches, like a modern backpanel). Made in vietnam, in my opinion by the same factory that makes Blackhawk and Sord items. I don't think it's more sturdy than the original.
It is now out of production since 7/8 years. Interesting trivia, there was also an AK specific version that lasted on the market for a longer time sold by a Belgian shop, Morane Tactical. That is because the AK vest and a british style chest rig also made by Karrimor named the "commando" or "congo" chest rig were contracted by Belgian government to equip Virunga Park anti poaching rangers, Congo having been under colonial influence by Belgium.
The rig




British Paras wearing pattern 83 vest, KFOR era. Soldier is wearing smock without underwear, which is not uncommon on patrol, smock being an important part of load bearing.

Are placards a new thing? Meh.

I already mentioned the arktis mini rig and how it came without shoulder straps to augment plce capacity. Here used with a body armor attached to its d rings.
Not a UK soldier BTW.

Picked up a current issue Vertus PLCE belt kit last month for £40

Comprises:
Belt
Yoke
Smoke grenade pouch
Frag. grenade pouch
E-Tool pouch
Waterbottle pouch
Ammo pouches (x 2)

(from memory)

Happy to dig it out to take photos if folk are interested?
It seems like a well designed bit of kit - a night & day difference to the '58 Pattern that I was familiar with from my stints

I'm keeping an eye out for the Vertus manual = has lots of high quality colour photos of all the items in their load bearing family, plus how they are worn/interact with each other, etc.

I'm also seeing a lot of Osprey made PLCE kit (now obsolete, ?) at very good prices.
May research those items as time allows and see what set I can put together
Been told of an Osprey armour carrier/chest rig system available locally,  but don't know if I want it as yet. It does have a host of stuff attached to it & is complete aside from armour inserts.

Busy repairing an Arktis (badged as Country Covers, it's the same firm) sniper drag bag.
Got it a few years ago at a good price, used. I have been straining it somewhat with an M24 and a 2nd rifle - so one of the strap anchor points is seeing thread/stitching failure.
An easy fix for a leatherworker

I'm personally a fan of the LC-2 gear over chest rigs and PC's but I haven't had a chance to try a PLCE set. I'm currently running 2x canteens, 3x ammo pouches, an M12 holster and a BDS buttpack. I've used tape, paracord, etc to modify it, but I would love to have a PLCE set in DPM. I know Fireforce Gear used to have some for £28, and that fits my tight budget a little better lol.

ETA: Firestorm Kit also has DPM sets @ £29, but they only come with two utility/waterbottle pouches instead of three.

I have been look at the british webbing style belt kit for a while.  I have chest rigs i have body armor.  But i am thinking that a belt only setup has it place.  I look at some of the uk web sites.  But not being able to get my hands on it im worried that it is airsoft stuff and will fall about once i get it.

Given the low cost of genuine DPM type PLCE sets I'd be surprised if any airsoft firms tried to "corner" the market & undercut prices

I have some of the big pouches and mediums for 308 mags on a U.S. LBV. Worked out good made a cheap setup for extra gear.

https://www.youtube.com/channel/UCKiR8FI-jZ4iSohllnVZZtQ

This is a nice channel that has many short reviews of popular UK parts of kit that are "ally", it's interesting and you can understand some of their choices. The reviewer is a soldier with a STRONG London accent with some military terms mixed in but I can understand it even if English is not my native language.

Good comparison between Trooper, Dragon supplies and Jayjays webbing, only Dixies Corner is missing.

Just picked up a few of the DPM pattern twin carriers for the Rifle Grenade, all seem to be 1997 dated and show zero signs of use

An interesting design. Two can be zipped together to make up the same "footprint" as one of the Bergen side-pockets, so they can either attach to the side of the Bergen, or be carried on the yoke assembly normally used to carry said side-pockets. I also read somewhere that 5 can be zipped together as one unit to make up a 10-grenade bandolier...
Picked up a few of the dedicated side-pocket yokes at the same time, again in DPM

Mkr just uploaded a small walk-around of the "field pack ai support", aka the air support bergen, which is the largest of the issue bergens at 180 liters capacity, 150 + 3x10liters detachable plce side pouches. It has aluminum internal frame and its sized to sit over pouches. Short but large