In some countries (including this one) to get a firearms certificate you have to have a strong steel concealed cabinet and keep it locked up. If the police come round to inspect your gun while you're out, and your wife/husband/SO/son/daughter unlocks the cabinet to show it to them... it is likely to be confiscated, because unless they are also a certificate holder, they shouldn't be able to unlock the cabinet and get the gun out.
as it happens, handguns are mostly prohibited here, but that's a different matter.