The door

At the bottom of the stairs in our block of flats there is this door. Now it doesn't have a number on it and no buzzer at the front door seems to relate to it.

Now I know it's not a cleaner's closet as that's round the corner under the stairs, so I've decided it's either an elaborate panic room for the residents of the block or some sort of secure bunker in case of WW3. My fall back position is that it's a back door into Narnia.

Mrs Al claims to know what's in there having seen the door open once, she says it houses all the utility pipes for the Block.

I'm sure she's not telling the truth and is not really in Manchester now, but is spending her time doing something fun behind that door.