I'm trying to remember now, what my childhood house had -- it was built in 1910, and had the Yale lock that needs a key from outside but no key to lock from inside, and you just turn the handle to unlock it and let yourself out, then simply closed the door shut from the outside and it was locked without need for a key. It had the little knob on the side of the inside part of it, to keep it "on the latch" unlocked if you were just running outside for a brief second, (or doing the gardening in the front garden -- we left the Yale "on the latch" when in the front garden doing anything, as we were right there watching the place anyway).
The Yale also had another thing to push (on the inside side of the door) which -- if I remember correctly -- set it to fully lock so that (I think) even the key from the outside could not unlock it. Dad would set that to lock for nighttime.
In addition, we had the chain just like others have mentioned. I don't remember if we had a mortice lock too -- we may have had but I'm not sure and quite likely we didn't. Finally at the top of the door or the bottom (or both?) we had a regular sliding bolt, which Dad also slid locked at night if we were all home for the night.
It was the 1960's and 70's in a "nice" part of north-east London near the Essex border, and the one and only burglary we ever heard of was the next door neighbor's, once, and that was it. Very different times. But we were still fairly lock conscious/security consious even though the times didn't feel very dangerous. We still locked our doors; well the Yale locked automatically locked. Our backdoor we were a tiny bit more lax about, leaving it unlocked if someone was home but expecting someone else back -- my Dad often came home going the side passage of the garden and in the backdoor. But if we were going to leave the house empty at any time, everything was locked/windows shut.
We never had a break in or burglary; it was a relatively safe neighborhood and period of time I guess.