Have just been to my local Tesco (Bromborough) and picked up a Targus Detatchable 3 in 1 Ethernet, phone and USB cable for £1.86
Connect to phone modems, ethernet networks and USB devices
No additional adapters for ethernet / phone connection are required
Cables can be detatched and used simultaneously
Can't find it on the Tesco site but the same product is £17.39 on Amazon.