I have a solution that
I think works but I don't have access to the equipment at the moment so I can't check for sure.
1) Buy a Sky (Netgear) DG934G ADSL modem/router on ebay for about £5
2) Reprogram it back to a Netgear DG834G version 3 using
these instructions
3) Switch off its DHCP server, fix it's own IP address and set up the wireless parameters
4) Leave the 'line' port disconnected
5) Attach up to 4 devices to the switch ports