Which version of the BT hub are you using?
Version 1 and 1.5 hubs can be used successfully in a master/slave context because they support WDS (Wireless Distribution Service)but version 2 hubs cannot.
Any wireless router that supports WDS can be used in this set-up, as long as the DHCP IP address server is switched off.
You should ensure that the master hub has its channel number option set to manual, and set it to the channel number that is currently running.
On the slave hub set the SSID to manual, and enter the same channel number that you saw in use on the master.
Set the WEP key on the slave to the same as that on the master. You can't use WPA because WDS doesn't support it.
Turn off the slave's firewall.
Un-tick the DHCP box, and click on 'apply'. You'll get two boxes - enter 192.168.1.175 in the first one and 255.255.255.0 in the second, then click 'add'.
Go into advanced settings and look for the IP Addresses. You will have a stack of 4 static addresses with the new one you just added at the bottom of the stack. Delete the top 3,deleting 192.168.1.254 last of all. Ignore the warning about losing the connection.
Now go into the configuration section that deals with access points, and tell it to scan. When you see the SSID of the master hub, select it and click 'apply'. Ignore any warnings about losing connectivity.
Go back into the master hub and scan for access points. You should see your slave appear in the list, and when it does, select it.
Now you should be able to connect to either hub wirelessly after rebooting.
Make absolutely sure that you use a WEP key, not WPA, or it won't work.