I almost knew all f what you said regards the US, but the complete centralisation of a pool of “sale” properties is interesting, I thought they didn’t like that kind of thing over there, you know something resmebeling communisim/centralised control? 
So essentially our system is that of smoke & mirrors… SURPRISE SURPRISE!
Well joking aside, I think it is a good idea.
Take DAFT, daft is grerat at showcasing of the digital potential of centralisisng all accomodation information to facilitate the myriad of tranasctions but its got a lot of FAT in its presentation.
For example there are a lot of the descriptions that are windy in their breath, a waste of pixel space. There is a lot of “plumping” going on .
Now how about this, if we go to the golden pages, we find the following,
Auctioneers, Estate Agents & Valuers (3896)
Letting Agents - Apartments, Flats & Houses (14)
Property Management (9)
Overseas Property Sales & Letting (3)
I would imagine the reason the other categories are so low “letting Agents” only 14?? Is becasue the Auctioneers, Estate Agents & Valuers also perform most of the same business so you find the majority of the listings there.
So lets take the number at approx 3800 Estate Agents, general selling agents. (I am presumming some agents sell other things like antiques and such like).
Lets imagine each agent has the follwoing on there books,
Agents x Properties = Avg National Inventory
3800 x 10 properties = 38,000
3800 x 30 properties = 114000
3800 x 50 properties = 190000
3800 x 100 properties = 380000
I believe it reasonable to estimate antyhing from 20 to 40 odd properties per agent, which give us a large figure.
I am guessing there could be anything up tp 152,000 properties on the market, thats an average of 40 properties per agent.
What else can we do but ring each one up and ask them?