Liz had never been seen by the police before! She'd only just come out "of hiding" when she started sleeping with preg lady's boyfriend. So she is this suspicious character who A. Has been hidden away all this time and B. Is on the run from police for killing her mums partner!
I presume unit B of monitor was in Len's flat because he was babysitting, preg lady went in there to get baby, did she even go in to her flat? I thought she went in to Len's and then in to the attic (he was the top flat).
Yeah I think we saw him leave the door unlocked? I might be imagining that! I guess leaving it open was ok - the house is not open, he knows everyone, he's walking down the stairs and up again. Not that communal, if you know what I mean. Baby didn't look old enough to wander off :-)