[Grammar] don't lets vs. let's don't

[bester]

Grammar-wise and meaning-wise, is there any difference between the following:

Don't let's tell the police.

and

Let's don't tell the police.

?

To me, the first option does not sound too intuitive, but I've got this in my notes from grammar classes so apparently this must be correct?

 

[emsr2d2]

To me, those are both non-standard.

Let's not tell the police.

 

[bester]

So you do would argue they are correct grammatically speaking?

 

[emsr2d2]

For me, they're not grammatical. You will hear people say both but if I saw them written down, I would mark them as an error and if I heard them spoken, I would assume the speaker was using lazy, non-standard English, or was a non-native speaker.

 

[philo2009]

The first is heard in BrE as an informal alternative to Let's not.
The second is blatantly ungrammatical and would not be used by any educated speaker.