Clear skies and gave it one more go. The tail appears to extend to a length of
32 degrees. There is the vaguest hint of it continuing to the Milky Way but I
think it's star alignments doing it, as on the 16th. Details on pic:
http://i727.photobucket.com/albums/ww271/Rob_Kau/C2011W318Jan2012invertfulltexts\
m.jpg

Here's the normally-processed version, with the comet barely visible:
http://i727.photobucket.com/albums/ww271/Rob_Kau/C2011W318Jan201211-34UTredsm.jp\
g

Here's a link to Lester Barnes' composite widefield from 16 Jan, showing about
35 degrees of tail and no extension to or through the Milky Way:
http://i638.photobucket.com/albums/uu109/Lester_045/Comet%20images/38c7df7a.jpg

Cheers -

Rob Kaufman
Bright, Victoria, Australia