I never’s! / I say’s!

[Coffee Break]

I read this part, "I never’s! / I say’s!", but am finding it difficult to understand it. Could you please let me know what it means? Here is the excerpt:

They passed from room to room—all got up regardless: thick carpets, deep soft chairs—shining furniture. The bathroom had a weighing machine in it, a huge jar of purple bath crystals, and a shower. The Stevens followed their host, wide eyed, speaking to one another in hushed whispers if they happened to be behind, but keeping up a series of enthusiastic “Well, I never’s!” and “I say’s!” if they happened to be in front of the procession and alongside their host, and Mr. Montgomery grew prouder and more expansive at every step.

- R. C. Sherriff, The Fortnight in September, Chapter 27

This is a novel published in 1931, which describes a fortnight in September in which an English family consisting of Mr. and Mrs. Stevens, Mary, Dick, and Ernie go on a holiday. One evening, they are invited to the tea party of Mr. Montgomery at his house. Now they are being shown around his house during the party.

Here, I wonder what this underlined part means.
It seems to me that they are giving compliments to Mr. Montgomery's house, but I am not sure what they are saying.

By "I never," (with "I never's" being the plural form of "I never" perhaps) would it mean "I have never imagined such a thing," and, by "I say", would it mean "That is what I mean"...? (But these are just my guesses. )

 

[Barque]

Yes, they're both exclamations.

I never - I never would have imagined.
I say - roughly--I have to say, how wonderful/how remarkable!

I've never really thought about what either exclamation means if you try to write them out in full.

 

[Coffee Break]

@Barque,

Thank you very much for the explanation.
Oh, so they are stand-alone exclamations, which do not have to be written out in full!

So they were saying, "I never would have imagined! This is unbelievable!" and "I have to say, this is wonderful!".

I truly appreciate your help.

 

[Tarheel]

@Coffee Break Yes, it's a kind of shorthand.

I never! - I never would have expected that to happen.

Conversational English is like that. (I imagine most languages are that way

 

[Barque]

So they were saying, "I never would have imagined! This is unbelievable!" and "I have to say, this is wonderful!".

As far as "I say" is concerned, I'd suggest you just try to understand the meaning behind it. As I mentioned, I've never really thought about what it means if written out in full. It's an exclamation to indicate a sudden thought, or that something's remarkable. It's old-fashioned now.

I say! I have an idea!
I say! Look at that!

When used for emphasis, it can be taken literally.
I did not do that, I say!

"I never" is easier to understand.

 

[5jj]

The expression is 'Well, I never'. We don't say it without the 'well'.