A title with a transposing note name

[Richard Shann]

I am trying to make a title (e.g. Sonata in F minor) which will
transpose when the music is transposed. I can do this by using
ChordNames for the name of the note in a markup using \score, thus:

\version "2.19.25"

\header {
  title = \markup {Sonata in\score {
\new ChordNames { f' }
\paper{
#(define fonts (make-pango-font-tree "Times New Roman" "Times New Roman""Luxi 
Mono" (/ staff-height pt 20)))
}
\layout{indent=0.0}
} minor}
}

\score {
  \new Voice { \clef treble s1 }
  \layout { }
}

In this I have tried to change the font of the ChordName (which defaults
to sans) by using the syntax at
http://www.lilypond.org/doc/v2.18/Documentation/notation/fonts#index-font-families_002c-setting
unfortunately the example has the \paper block outside the score block
while my version has it inside and this causes an error.
Can this be done by some variation on the route I have set out on, or do
I have to put up with the sans note name?

Richard