I grew up in the countryside and used to do all sorts of camping, sleeping out in people's gardens, we used to go off and play unsupervised in the woods, did brownies, guides etc...
Where I live now, there isn't a chance in hell I'd let a 5 and 8 year old sleep out in my back garden - I sure as hell wouldn't. From urban foxes to stray dogs, drunks wandering about at night, burglars on the prowl and a scary number of sex attackers round here. Just last night the police helicopter was hovering for ages round and over the park by me and numerous sirens and shouting (not unusual here) then I was woken up by people fighting on my drive in the early hours. Even the frequent bangs could scare a child, it's likely fireworks, especially with Eid, but living right by Moss Side, you just don't know. There was a bullet hole in one of my windows when I moved in.
To be fair, I wouldn't want to bring up a child living here and live on my own but unless you know the location and potential dangers I'm not sure if a reasonable decision could be made without considering all the circumstances.