check out picket in the "index" tab at the head of the blog
Click on subject of interest shown on the right under the heading "labels" to see all relevant posts
To look at letters (and some replies) sent to politicians and newspapers, scroll down the index on the right hand side and select the appropriate heading.
Note the blog allows multiple labelling and all letters to politicians are under "letters to pollies".
If you scroll down and cannot go further, look out for icon "Older Posts". Click on that to continue