My first real attempt to build a temperature sensor that would be suitable to mount on the wall was not a success. The telephone coupler from a diy store was just to fiddly to fit the bits inside. However, I still liked the idea so I tried these Junction Boxes from ScrewFix. I paid 4 pounds for five on the off chance they might be okay. Well, they were better than okay.
My Tech Supplies order  arrived today, so this evening I made up my first temperature sensor. We got a simple sensor working along the lines of the one described the web site for the digitemp software that we are using to read the sensors from the computer.