The dad, who is also Peter Cushing, then decides to show Ian his new invention, which is a literal Tardis, which is like a police themed phone box that is bigger on the inside than on the outside and also travels through time.
The smallest daughter helpfully explains that this is "science" and not magic. Then Ian's girlfriend, one of the older daughters wanders in and kisses him, knocking him over so that he knocks a level and teleports the Tardis to a swamp planet somewhere.