[13 Nov]
As my threads have lots of replies, I end up with a forest of ">" characters which makes it difficult to read
earlier quoted entries (what with word-wrapping of the browser).
I thought to replace the ">"s by a simple date entry prepended to the start of each reply. - much as I have 
given at the top of this initial entry.

So this is what I put in the config file:

....
Time format = %a %d %b %y
Date format = %d %b
Prepend on reply = [$date] \n
...

The time is used in the string for the Thread display.

Only I don't get the date, with the date format, prepended to replies but the time, in the time format, as

[Wed 13 Nov 13]

Now this is hardly a disaster, but any ideas why the date formatting is being ignored?