The object of the lesson is to ensure the scroats who will try an steal your car are stopped by cloning the 'key'. If you store the key in a tin at home and only take it out to enter and start the car you should be OK. I am not a scientist but it is something to do with the' Faraday cage' effect which blocks any intrusion.
If you have ever watched the idiot three in Top Gear, Richard Hammond was put into a VW and then they pulsed a lightning bolt down on the car. I seem to remember it was in Germany where they have the testing equipment. Hammond was suitably concerned. The lightning bolt hit the top of the car and then grounded. They explained that it was not the fallacy of the tyres protecting you but the car was in fact a Faraday Cage. ie a metal case. Hammond was completely unhurt.
With your keys in a metal tin it is the same effect. I have just bought a wallet to put the key in. The key has to be put in a section which has a 'metal. lining. It is made of leather and was about Ł7 for two off Ebay but if your tin works what does it matter what it looks like.
I had no idea that a brick wall was no way of stopping them cloning the key signal. We keep the keys in a drawer in the kitchen NOT on a hook behind the front door.Trouble is when the boffins stop the scroats they merely invent another way to steal what is not theirs.