Archaic Past Conditional

I'm unsure as to how to define the tense in a sentence such as the following:

 'Behind the doors there were to be other chambers, possibly a succession of them, where we should find the coffin lying.'

This perhaps isn't the best example, but it's the only one I have available to me now   It's from an early 20th century British author, and - coming from a part of England where such anachronisms are used frequently - is perhaps a very 'British' thing.

I must stress that the use of 'should' [despite what the quotation above may suggest in its condensation] seems in no way to reference the conditional in any standard, modern form - the whole passage is written in the past. What I'm interested in is how 'should' is defined: is it, for example, a 'past conditional'?

I apologise for how unclear I've made this: hopefully someone out there will know what I mean. Just in case, though, I'll try to think up some more examples.

Any help would be much appreciated.

Brainflash...could this be an example of the [now largely defunct] English version of the Imperfect Subjunctive? I don't know how far one can change 'would' to 'should' for such a tense, but...it seems reasonable. Looking at Wikipedia to find an example, I find:

 'If I were rich, I would retire to the south of France.'

 And this seems to fit perfectly with the 'should' of the previous extract:

 'If I were rich, I should retire to the south of France.'

 Do you not think? Remember the nuance...'should' in this instance makes no direct reference to anything being conditional: 'would' and 'should' can be used completely interchangeably in the form I'm describing. It might be an archaic British peculiarity [probably much like the Imp-Sub in general], but...I think the Imp-Sub classification seems to fit wel, no?

Then again, I could be going down completely the wrong track. All help appreciated.

I'd just consider it a subjunctive mood form:

http://en.wikipedia.org/wiki/Subjunctive

Also, I think that a more clear version would be:

Behind the doors there were to be other chambers, possibly a succession of them, where we thought we should find the coffin lying.'

With this, it looks like reported speech.

The present should find form: 

We think we should find the coffin lying.

translates into the similar subjunctive/conditional form (see Swan) in the past:

or into

We thought we should have found the coffin lying.

depending on where in the past you want to place the finding.  

BTW, there's nothing archaic about any of the above, once we thought is inserted. 

badegine

 'Behind the doors there were to be other chambers, possibly a succession of them, where we should find the coffin lying.'

Hence, this substitution in mind, the sentence is equivalent to the one which ends:  where we would find the coffin lying.

It is therefore nothing more than the backshift of where we will find the coffin lying.

Just as will find is the future of the present, would find is the future of the past.

A paraphrase might be:  where (eventually) we were going to find the coffin lying or where we were about to find the coffin lying.

I don't find anything remotely subjunctive or conditional in the sentence.

The future of the past is used frequently in narrations to alert the listener (reader) to events which happened after the time that is central to the point of view of the narrative as it has developed to one particular point in the narrative.  The events which then were about to happen may or may not be referred to again later in the narrative.  It seems to me that I hear this tense most often in documentaries -- but not with the old-fashioned substitution of should for would after I and we, of course.

Little did we know at the time that we would soon regret the decision we made.  (Older form:  that we should soon regret ...)

The political situation was bad, but in the next decade things would take a dramatic change for the better.

Several more disasters would befall our heroine before she finally triumphed.

CJ 

PS.  I don't see any anachronisms here either. 

Thank you all - brilliant. Good to know I was just overthinking the whole thing.

Out of interest, would there be a linguistic term for such a substitution?