Use of "you and I" in TS Eliot's Prufrock

I've long been a fan of T.S. Eliot's poem The Love Song of J. Alfred Prufrock. However, it seems to me that his use of "you and I" in the opening lines is incorrect.

Let us go then, you and I, when the evening is spread out against the sky

My reasoning is that "you and I" replaces "us" and you wouldn't say "Let I go then", so it should be Let us go then, you and me.

Is this Eliot taking poetic license or am I just wrong?

The question can, as Edwin has said, be related to questions about ‘between you and I’ and ‘They invited my wife and I’. The fact is that English pronouns, particularly the first person singular personal pronoun, are unstable, and have been for a long time. To me, as a fairly well educated speaker of British English, there is nothing ungrammatical about Eliot’s use of ‘you and I’ in that line. He was too good a poet to use it only to make a rhyme with ‘sky’.