A Grammatical Conundrum

Not the first, but I'm dealing with them one at a time - hence the absence of the word "conundra" in the title.

So...

"they would then have kept with you until such time as there were cause for you to be confined or, for want of proper cause, an escort were unwarranted"

"they would have" - past, conditional... "until" and then, er, the past subjunctive of "be" to convey the (unreal past) but future looking implied secondary condition?

Is that right, or is there a better way?

I would that English were simpler sometimes!