On Mon, 17 Dec 2012 08:41:59 +0000 (GMT), Dave Liquorice wrote:

Is there a 'range extender' that will sit on the cat5 network and
re-radiate/receive the BT Hub transparently in each of the buildings.

That is what your collection of ethernet connected wireless hubs
already do.

Second thought(s) are these "wireless hubs" really a wireless router with
WAN and LAN ports or a plain wireless Access Point (LAN port(s) only)? Is
the ethernet cable plugged into a WAN or LAN port? If a WAN port is the
box configured into bridge mode? Where do devices connected to the
wireless side getting their IP address etc from the DHCP server in the AP
or from the BT Hub? Don't guess look at the DHCP tables in the AP(s) and
BT Hub.

--
Cheers
Dave.