I live on the 3rd floor and my street doorbell went once, and as I was expecting the electric meter reader I released the lock and began making my way down the communal staircase to meet him, but I heard footsteps and voices coming up the stairs so I called out "Is that the meter man?"
"No" a mans voice replied, "we're Jehovahs's Witnesses".
So I quietly u-turned without a word and crept back to my flat and shut the door.
I heard puzzled voices wondering where I'd gone and eventually they vamoosed..