Trendnet TEW-435BRM Wireless ADSL Router supporting 802.11B and 802.11G £10 in Asda Living. Plenty in stock in Leeds Crown Point retail park today. May also be in Wallmart super centre stores. Note there are two different versions for the same price. The one you want to buy it D1.0R as this is the most recent of the two they had in stock. D1.1R is newer if you can find one. These are identified by a small sticky label on the reverse. They also have a cable broadband version for £15 for Virgin etc.
Setup seemed relatively easy. The only point I think most people would stumble on is it it says it automatically checks your connection, then it asks if you need to login to your ADSL connection while automatically selecting no log in. Most users will need to change this.
Some things it has (not a complete list). 4 lan ports. QoS based on either rate control/priority (good for VOIP connections etc).
Interestingly I have a net connection speed increase giving 5mbps where with the previous I only got about 4mbps. Will give it a proper online test comparison with the old one in a bit to check if there is a real-world increase. The quality of the plastic it is in is quite poor and felt a bit like a toy but you can't really complain for the price.