Hi
I have two beagles, male and female both 21 months old, which I have had from puppies. They have only ever been allowed in the kitchen and garden.
Recently, my male dog has taken to walking or lying on the kitchen table!
He only does this when I have left the room and I rarely catch him at it. As soon as he sees me enter the room, or more usually hears me coming he jumps off leaving dusty paw prints behind.

Previously I've had to change the kitchen door handle to a knob as he had learned to open it  (yes and pull the door towards him) to sneak out of the kitchen and slink upstairs when we are busy in other parts of the house. After I foiled this plan with the knob, he would jump into my chair when I left the room, or steal and destroy the last thing I had been looking at; newspaper, address book, children's homework etc. Is he challenging me? Or does he think he's a human?  

Any advice?

Just makes me chuckle, our dog has never been allowed upstairs but the last couple of days if we have been upstairs he has ever so quietly crept up. I think he is just testing the water see what he can get away with.