subject and predicate

We are preparing a lesson plan for a college grammar class and realized that we werent sure what the subject and predicate are in this sentence.

There once was a painter named Gregory.

Could you help us please?

[Casiopea]

If there is existential, then you can replace it with the true subject, like this,

A painter named Gregory once was.

There's also something called secondary predication that you may or may not want to look into: http://linguistics.berkeley.edu/wccf...ts/kalluli.pdf

Here's a nice, easy resource: Subject and Predicate

All the best.