What proportion of total bandwidth is BT WiFi restricted to?

Does anybody know what proportion of total bandwidth is BT WiFi restricted to? BT WiFi piggy backs off BT Home Hub routers - giving other users their own login to the internet, off your connection. But I am just wondering, what percentage of my total bandwidth are other users restricted to?
Many thanks.

Looks like 4 Mbps up and down on mine http://www.thinkbroadband.com/speedtest/results.html...

And isn't that flexibly?

So that if nobody is using that side of the OP's WiFi, it is still basically available to the OP?

Also, would not the degree of allocation be more significant on the Broadband side of the connection rather than the WiFi, the latter seems to be typically quite large, in my own case (not BT) around 300 Mbps, compared to my Broadband being generally about 37 Mbps Down, 9 Mbps Up.


Apart from which, any user of that "public" part would have to be quite close to the Hot-Spot, say about 50 Metres.