Not a drug deal but I had the Police out to a situation yesterday in town, 2 young children in a parked car, no sign of an adult after 10 minutes. Dad turned up, a lucky chap, bet he does not do that again......... 
Good call Mike.
I saw an unattended baby in a front garden the other day - right near the gate.
Watched for 10 mins, no sign of life.
Ended up knocking on the door and asking what they thought they were doing!
I'm sorry .. but I see nothing wrong with this at all, my children spent hours in the garden "unattended" as you put it .... but a single sound and mums radar would have been there in a moment.
You would have been told, in very strong terms, to mind your own damned business if you approached me in that way - in uniform or not !!
There is far too much "nanny state" without individuals joining in IMHO.
Rant over ... 
Under normal circumstances I would agree with you Nige, but knowing the area and it's problems well, we weren't satisfied to walk away without at least checking the parents were nearby.
Reasons? The baby was left in the front yard of a house, on a pavement, directly on, and visible from, a street blighted by drugs, hookers, and other issues.
You are also not aware of the time of day this happened - which again, was a VERY unusual time to leave a baby unattended, in such an area.
It's not somewhere I enjoy walking around alone, let alone leaving a child.
We'll have to agree to disagree mate - too quick to condemn without full posession of the facts.
I'd rather risk poking my nose into something and risk being told to shove off, than walk on by, have that child harmed, and have that on my concience...