Lyrics not lining up properly

[Cameron and Trudy Horsburgh]

Hi folks,

I''m typesetting a piece of cornet music which requires the musician to 
sing every once in a while. However, each separate instance of lyrics 
(presumably in the same context comes out a line lower than the one 
before it. It's a bit hard to describe, so here's a cut down version of 
what I'm trying to do (I get the same result). I've defined the Lyrics 
context earlier in the piece and used it without any problems. It sits 
at the same height as does the first instance of my example here. Any 
ideas what I'm doing wrong?

\version "2.2.0"
\score{
\notes{
\relative c''{
\key bes \major
   \time 6/8
   \partial 8 f,8 | bes(d) f, bes(d) f, | bes( d4 )~ d4
       <<
           {ees8^"(Sing)" | d4 d8 c4 c8 | bes4.~bes4}
           { \context Lyrics \lyrics {A8 hunt4 -- ing8 we4 will8 go.4.}}
       >>
   f8 | bes(d) f, bes(d) f, | bes( d4 )~ d4
       <<
           {ees8^"(Sing)" | d4 d8 c4 c8 | bes4}
           { \context Lyrics \lyrics {A8 hunt4 -- ing8 we4 will8 go.4}}
       >>
       }}}

Cameron