Little did he know...

I think it depends, in great part, upon your point of view. Some authors are very successful with an intrusive third person narrator (that narrator need not be the author). If the established PoV is one of the characters, it would be harder to make "little did he know" work. If the character is reflecting the past or communicating in a narrative way, it could work.

One way in which it can work, at least potentially, is at the end of a scene to build suspense. That doesn't mean it's the best way to build suspense of course. For instance, just as much suspense might be built by having 'She was to revive that opinion shortly' without the 'Little did she know'. Although 'Little did she know' might add a needed transition.

Like so many things in writing, this is one of those phrases that we definitely should ask 1.) does it do harm to the work? 2.) does it add add enough? If it's doing more harm than good or is a wash, cut it.

Thanks for replying, Andy.
I found this article which seems to suggest not using it - of course, it's just another opinion. http://airshipdaily.com/blog/06242014-origin-of-cliches
For me, something like - she was to revise that opinion shortly - is a cheap way of inviting the reader to read on because the story is going to get more interesting. In the pages before, we get a lot of the character's thoughts - italicised sentences of them. So, we're very much in the character's head.
I wouldn't have noticed this 5 years ago, but now I write - all sorts of things jump out.
For me, it's breaking the 4th wall - but then, I've got loads to learn.

I go back and forth on this one. I try not to use it in my own writing, but I don't always mind it in someone else's work--as long as it's done subtly and artfully. When done incorrectly, it can certainly break reader immersion. The specific phrase, 'little did s/he know,' I'm not fond of.

mmm... can it seem subtle or artful to another writer!

I've read a few more chapters and it's not been done again. For ne, it didn't add any value where it was done - though as I said, the published author didn't actually write Little did she know.

Perhaps it's just one of those things that bug me.

I often absolutely adore it as a reader. So I think any writing advice saying not to use it just because would be advice I'd avoid personally.