Key change with clef after the bar line?

[Alasdair McAndrew]

In my current project, I'm trying as far as 
possible to replicate the spirit of the original 18th century publication, 
in which a key change has a clef printed, and both after the bar 
line.  In one piece, there's a segno in the middle of a bar, with such 
a key change.  In standard Lilypond, this micro-example shows that the 
printed clef comes before the bar line (I've left out the segno marker and 
all other markers outside the score):

global = {

  \language english

  \clef treble

  \time 4/4

}

\relative c' {\key c \major c4 d e fs | g a \bar "||" \set Staff.forceClef = ##t \key c \minor bf c | bf af g f | ef d c2 }

But modern practice is to put the clef before the double bar, and the key change afterwards.  I want the clef to come after that double bar.  According to the documentation, this can be changed with "break-alignment", in particular with:

> \override 
> Score.BreakAlignment #'break-align-orders =
> #(make-vector 3 '(span-bar
>               
>               
>  breathing-sign
>     
>                     
>      staff-bar
>                     
>          key
>                     
>          clef
>     
>                     
>     
>  time-signature))

However, in the mini example just given above, adding that override in the global declaration has no effect.  I tried changing the order of "key" and "clef" in the override, again with no effect.  (When I tried his in a larger piece, the key change was printed on the bar-line!)

Is there any way I can notate a key change, at a segno with an extra bar line, in order: bar line, clef, key ?

Many thanks,

Alasdair

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