3rd Person Imperatives

Halliday & Matthiessen (2014: 166):

We may also recognise a third person imperative form as in Lord save us!; these are rare except in exclamations and in young children’s speech (e.g. Daddy carry me!). Here, too, there is a Subject but no Finite operator. These never occur with pronoun Subject; if the Subject required is a pronoun it will always be accompanied by let as in let them beware!.  This is therefore comparable to let me, and also to let us, from which, of course, the modern let’s originally derives. (The older variant let you ... no longer occurs.)