strace kmail --nofork shows:
  getdents64(37, /* 10 entries */, 4096)  = 312                                                                                                                                                                                                
  close(37)                               = 0                                                                                                                                                                                                  
  access("/usr/share/myspell/dicts/en-GB.aff", F_OK) = -1 ENOENT (No such file or directory)                                                                                                                                                   
  futex(0xa7219dc, 0x80 /* FUTEX_??? */, 2^C <unfinished ...>   

ls -lah /usr/share/myspell/dicts/                                                                   
total 140K                                                                                                                      
drwxr-xr-x 2 root root 4.0K 2008-09-27 06:30 .                                                                                  
drwxr-xr-x 4 root root 4.0K 2008-09-27 06:30 ..                                                                                 
-rw-r--r-- 1 root root 127K 2008-09-22 05:49 DicOOo.sxw                                                                         
lrwxrwxrwx 1 root root   30 2008-09-27 18:28 dictionary.lst -> /etc/openoffice/dictionary.lst                                   
lrwxrwxrwx 1 root root    9 2008-09-27 18:28 en-AU.aff -> en_AU.aff                                                             
lrwxrwxrwx 1 root root    9 2008-09-27 18:28 en-AU.dic -> en_AU.dic                                                             
lrwxrwxrwx 1 root root    9 2008-09-27 18:28 en-GB.aff -> en_GB.aff                                                             
lrwxrwxrwx 1 root root    9 2008-09-27 18:28 en-GB.dic -> en_GB.dic                                                             
lrwxrwxrwx 1 root root    9 2008-09-27 18:28 en-US.aff -> en_US.aff                                                             
lrwxrwxrwx 1 root root    9 2008-09-27 18:28 en-US.dic -> en_US.dic    

dpkg -S en-GB.aff         
myspell-en-gb: /usr/share/myspell/dicts/en-GB.aff

dpkg -L myspell-en-gb
/.                                               
/usr                                             
/usr/share                                       
/usr/share/myspell                               
/usr/share/myspell/dicts                         
/usr/share/myspell/dicts/en_GB.aff               
/usr/share/myspell/dicts/en_GB.dic               
/usr/share/myspell/infos                         
/usr/share/myspell/infos/ooo                     
/usr/share/myspell/infos/ooo/myspell-en-gb       
/usr/share/doc                                   
/usr/share/doc/myspell-en-gb                     
/usr/share/doc/myspell-en-gb/copyright           
/usr/share/doc/myspell-en-gb/changelog.Debian.gz 
/usr/share/myspell/dicts/en-GB.dic               
/usr/share/myspell/dicts/en-GB.aff               

sudo apt-get install --reinstall myspell-en-gb 

ls -lah /usr/share/myspell/dicts/
total 688K                                
drwxr-xr-x 2 root root 4.0K 2008-09-30 16:46 .
drwxr-xr-x 4 root root 4.0K 2008-09-27 06:30 ..
-rw-r--r-- 1 root root 127K 2008-09-22 05:49 DicOOo.sxw
lrwxrwxrwx 1 root root   30 2008-09-27 18:28 dictionary.lst -> /etc/openoffice/dictionary.lst
lrwxrwxrwx 1 root root    9 2008-09-27 18:28 en-AU.aff -> en_AU.aff                          
lrwxrwxrwx 1 root root    9 2008-09-27 18:28 en-AU.dic -> en_AU.dic                          
-rw-r--r-- 1 root root  28K 2008-09-16 15:06 en_GB.aff                                       
lrwxrwxrwx 1 root root    9 2008-09-30 16:46 en-GB.aff -> en_GB.aff                          
-rw-r--r-- 1 root root 516K 2008-09-16 15:06 en_GB.dic                                       
lrwxrwxrwx 1 root root    9 2008-09-30 16:46 en-GB.dic -> en_GB.dic                          
lrwxrwxrwx 1 root root    9 2008-09-27 18:28 en-US.aff -> en_US.aff                          
lrwxrwxrwx 1 root root    9 2008-09-27 18:28 en-US.dic -> en_US.dic