The queue is both tempestuous and timid. Indeed, it is large enough to contain many human emotions along its winding length, a length that is only just contained within the confines of the post office.
At the bottom end of the queue, people have settled into a quiet ennui, but at the end nearest to the service points they are hostile and tetchy.
From here, it is clear that only two of the eight points are being staffed - a ratio that many in the queue rightly conclude to be the cause of the queue's length.
The authors of reports charting the demise of the Post Office have clearly not been using this one. It is full of people applying for passports, paying utility bills, posting packages and collecting foreign currency to be taken back to the home country - for this borough, one of south-east London's less swanky, is notable for its cultural and racial diversity.
Consequently things are often close to organised chaos in this branch, yet somehow it works, perhaps because certain informal customs have evolved. These customs are unspoken, but they are keenly observed and are a direct result of the post office's location. People around here carry knives, sometimes guns, so anything that might publicly affront their dignity - such as shouting at them - is avoided. Instead, when not drunk, we nod and shuffle.
The two men serving are quick, but not as quick as some of those queuing would like them to be, and resentment seeps through the waiting crowd to the point where the queue snakes back on itself. Here, an uneasy accommodation between the discontented and the bored prevails temporarily among those on either side of a partition cord.
But one man in his thirties wearing a corduroy jacket and narrow brown brogues is not accommodated and makes known his displeasure. He holds his chin above his neighbours as if they smell and, tight-mouthed with disdain, he grunts and curses as if his efforts alone will move things along.
Apparently this works, as a woman arrives alongside the two men behind the counter. However, she does not open her station immediately but sets about the task of arranging her pens and stamps first.
“Here, is your window open or not?" a voice shoots out of the queue. It is in a different register, socially and tonally, from everyone else's - a difference sharp enough to make most of the people in the queue look up. Even before I look up, I know it's going to be the man in the corduroy jacket and brogues. It is. The woman behind the counter is not used to being addressed in this way and, taken aback, says nothing. So the man barks again, "Well, are you going to open?" In our minds, we reach for our guns and knives.