Hi LWB! I did the signaller assessment in 2012 and found the lift tone part the most tricky! What they do is use different tones to signify going up or going down, The higher the tone its goes up a floor and the low tones goes down a floor . They will do it in random order like start at ground "UP UP UP DOWN UP UP", so something like that and you have to say what floor it ends up on. Everyone is in the same boat so they will play it loads for practice, so if he doesn't understand they will play it until he does (In my group we must have heard the practice test for about 10 minutes). Hope all goes well for him!
I did the assessment in Euston in late 2012 also and a couple of people in my group really struggled with the lift tone part of the test and kept asking for more practice goes but if you go in after a good night's sleep and concentrate well it should not be a problem. Has your son got a date for his assessment yet?
Its a preposterously easy day if you concentrate. I thought it was a bit bizarre, as it didn't really seem to sift anyone out!
Just tell your boy to relax and don't sweat it. They explain everything really well, and let you practice immediately before hand and ask questions if you need to.