They do work. I got a sheet of 18mm thick mdf cut to 31cm x 65cm and used a router set to 6mm to cut an air channel under where the laptop sits. Air flows under the laptop and i get a nice mousemat section for gaming on the sofa. Dropped temps while gaming from 95degrees on cpu to about 80.... which is very good for my chip.
Depending on how old it is you might want to pop it open and clean the fan/heatsinks too.
I've got one of those usb powered belkin trays to stop it transferring heat when on your lap. The fan is too noisy and the laptop slips off it if its not flat.
I'm thinking of doing something like this.
Out of curiosity did you used to live in Syston?