Just a general question, but can anyone tell me the purpose of a...

Just a general question, but can anyone tell me the purpose of a bid to buy 1 single share (see order at 2.7 today)..

I understand that at the end of an auction, a single share trading hands could make the difference to push an open/close up or down a pip, but I can't think of any reason to have a standing order for 1 share.. other than maybe you get a buy confirmation alerting you to it being at that price, but setting up an alert for that would be easier and more reliable..
It also can't be used as a placeholder in the queue at that price correct? As e.g. amending the volume would just send it to the back, as if you had just placed a new order...

I just don't get it..