When was the door shut? David Payne. Rules out wandering off.

[Robittybob1]

When was it shut? David Payne says "no one could have got in that way if that's the way they entered as the door was shut"
Lets go through the timeline:
The front door was shut when the McCanns left their apartment.

If then someone enters via that front door obviously they have a means of opening the door.  It is no longer shut, then is it.
So when he says "as the door was shut" when is he making that assessment about the door?

David Payne Quotes:

and again "I said well look how do you know that is the case, and err you know again I, I can't remember the exact words then, but I was very interested in finding what the state of the apartment was like when she'd got there to see who'd left err doors open or etcetera. And from my point of view you know the things that were, I think it was really pertinent to me was that there was two, there was two gates on the back entrance from that apartment. There's the gate which is immediately bring, you know brings you on to the err the road and then there was another child gate, that was at the top and I, you know, and given the fact that the front door was shut".

 Reply "Err we, you know, we ran up err to the apartment, you know, with, with err you know Kate and Gerry err and you know for me, I just wanted to know, as I say, about the access to the apartment, were those gates open, err because in my mind was that if the front door was shut there was no, you know there won't be, you know there was no way that she could have wandered out that way and nor would they have gained access in that way. Err also obviously the, the, the issue with the, the shutters had been raised, was brought up err you know on the way up as well and then I was asking about the gates being shut at that back and she said well both gates you know were shut, so in my mind, you know, that had ruled it out that Madeleine had err had wandered off."

[Robittybob1]

David Payne is not saying the door was shut at all times,  for someone may have entered through that door.

[Robittybob1]

https://www.youtube.com/watch?v=dXtBWNCFt7U&feature=youtu.be&t=518 we see Gerry uing a key to open the front door.
Unusual action too IMO.
He seems to hold the latch back for a long time I think I would have released the torque on the key a lot sooner myself.

[Robittybob1]

Matt Oldfield's rogatory explains what David is trying to say.  Matt says "you had to turn it to go in and so it would snip, erm, you couldn't really shut it with the lock on," 
You could not just slam the door shut you had to withdraw the latch bolt and the secondary lock bolt (for want of a better description).
http://www.mccannpjfiles.co.uk/PJ/MATTHEW-OLDFIELD-ROGATORY.htm

   "4078 'Okay. And this door here, what was the door like''
Reply 'Erm, brown, erm, big, brown and wood, brown and wood like. There was a lock, erm, it sort of, you know, one of those you turn twice with the key. And I think, and sort of I think a round, or was it like a lever handle, I can't remember what the handle was like, I think you had to turn it to go in and so it would snip, erm, you couldn't really shut it with the lock on, but I think if you didn't lock it up here you could then just open it and shut it, I think you had to actually lock it to, it wasn't like a Yale thing that, erm, stops you opening it again, I think'"

 

[Robittybob1]

Russell O'Brien confirms this "We were conscious that, that, erm, if you, you only do one lock on the main door then it can be opened from the inside but if you double lock it then, then, then you need the key to get in or out”.
1578    “Yes”."

One lock means close the door. Results in a door closed but not deadlocked - requires the use of the key from the outside to achieve this.

[jassi]

Russell O'Brien confirms this "We were conscious that, that, erm, if you, you only do one lock on the main door then it can be opened from the inside but if you double lock it then, then, then you need the key to get in or out”.
1578    “Yes”."

One lock means close the door. Results in a door closed but not deadlocked - requires the use of the key from the outside to achieve this.

This might explain why the cleaner was able to gain access to another guest's apartment, even though they had claimed to have locked it - they hadn't double locked it.

[Brietta]

This might explain why the cleaner was able to gain access to another guest's apartment, even though they had claimed to have locked it - they hadn't double locked it.

I think there is a fair chance the lock might have been faulty or even might have been tampered with at some stage ... at least one couple took pains to ensure they were not disturbed, but to no avail ... "We noticed that the cleaning personnel entered the apartment after one knock and did not give us time to respond. This was a bit bothersome and for this reason we would lock the door, and would leave the key in the inside lock.

After this precaution, the next day, the same thing happened and the cleaning woman entered even though the door was locked with the key in the lock.

We never found out how it was possible for a cleaning woman to enter after we had tried to prevent it."
http://www.mccannpjfiles.co.uk/PJ/CARLO-D_AMBROSIO.htm

[slartibartfast]

I think there is a fair chance the lock might have been faulty or even might have been tampered with at some stage ... at least one couple took pains to ensure they were not disturbed, but to no avail ... "We noticed that the cleaning personnel entered the apartment after one knock and did not give us time to respond. This was a bit bothersome and for this reason we would lock the door, and would leave the key in the inside lock.

After this precaution, the next day, the same thing happened and the cleaning woman entered even though the door was locked with the key in the lock.

We never found out how it was possible for a cleaning woman to enter after we had tried to prevent it."
http://www.mccannpjfiles.co.uk/PJ/CARLO-D_AMBROSIO.htm

It is fairly standard in holiday accommodation for it to be impossible to lock staff out unless with a chain.

[Eleanor]

It is fairly standard in holiday accommodation for it to be impossible to lock staff out unless with a chain.

I believe that the key was left in on the inside of the door.  With some locks this prevents people from opening the door from the outside, and with some locks it doesn't
I do have personal experience of this.

[Angelo222]

It is fairly standard in holiday accommodation for it to be impossible to lock staff out unless with a chain.

Staff have to be able to access all facilities at all times for obvious reasons.

[sadie]

Russell O'Brien confirms this "We were conscious that, that, erm, if you, you only do one lock on the main door then it can be opened from the inside but if you double lock it then, then, then you need the key to get in or out”.
1578    “Yes”."

One lock means close the door. Results in a door closed but not deadlocked - requires the use of the key from the outside to achieve this.

Agreed, but the door still requires a key to get in from outside, even when only closed.  It could be termed single locked rathger than double locked, or deadlocked.

Even single locked/latched like that, it still requires a key to enter from outside.  From inside a slider or a knob that is turned, is used to open the door  No key required from inside.

[Robittybob1]

It is fairly standard in holiday accommodation for it to be impossible to lock staff out unless with a chain.

Their method was not a solution to the problem.  it would have to be a very old fashioned lock for the key to activate the same barrel.  The key would then need to be shaped  with a degree of symmetry like the old Legge keys or as in the pic "Union" keys. 

[Robittybob1]

Staff have to be able to access all facilities at all times for obvious reasons.

The main problem in the case quoted was that the cleaners came in after just one knock and didn't give the occupants sufficient time to expect visitors.

[Robittybob1]

Agreed, but the door still requires a key to get in from outside, even when only closed.  It could be termed single locked rathger than double locked, or deadlocked.

Even single locked/latched like that, it still requires a key to enter from outside.  From inside a slider or a knob that is turned, is used to open the door  No key required from inside.

Sadie did you stay in one of the apartments when you were there?  What you say here is 100% in line with my understanding, but the real point I'm trying to make, and it is emphasised with the way Gerry held that key rotated as he opened the door, that the key has to be used to "single lock" the door from the outside. (did you see that video?  found it https://www.youtube.com/watch?v=dXtBWNCFt7U&feature=youtu.be&t=518 ) 

So you end up with a situation if there are more than two people doing different things that day, and there is only one key issued, when it becomes impossible for them both to leave the apartment locked in some situations, unless the person inside manually closes the door from the inside and has the key to lock the door when they leave.
But that means the last person to leave has to be the first person home as well otherwise that person will arrive back at the apartment and the other person has the only key. 
The Paynes solved this by just leaving the key under the door mat.  In their case with 3 adults all doing different things keeping track of how to lock the door became problematic and hiding the key under the door mat during the day was the solution.

[Robittybob1]

A real stupid and dangerous situation develops if the person leaving has the key and double locks the door making it impossible for the person inside to let themselves out. Not so bad on the ground floor but when the balcony is several floors up they are stuck.