Who would be knocking on my front door that time? Well, I know the family upstairs are a bit, how shall I put it, unconventional, but I wouldn't expect this from them.
The curious coincidence was that on Friday I had been woken up by a knocking on my front door - at 5 to 3.
Now, to be blunt, no living thing is going to be that regular. I am wondering whether it's my boiler - I have it on overnight as the electricity is cheaper then, and it is close to my bedroom (it is in a hall cupboard, with its door right next to my bedroom door and I sleep with my bedroom door and windows open to get a flow of air). I sleep with earplugs in, so when the noise wakes me, I instinctively think it's further away and some process in my mind rationalises it as someone knocking on the door.
But why wasn't I woken Saturday and Sunday? Maybe as I don't work those days, so there was no part of my brain listening out for the noise of an alarm to wake me up.