Reducing space between subject and first paragraph in scrlttr2

How do I reduce the vertical white space between the subject and the first paragraph when the subject appears after the opening?

I'm a new koma-script user but couldn't find anything in the manual on this. I am using scrlttr2 2003/01/31 v2.9n LaTeX2e KOMA document class. I need the subject to appear afteropening. When I do this I get a very large vertical white space between the subject and the first paragraph. Also the subject is poorly vertically positioned - its very close to the opening and a long way from the first paragraph.

Any help gratefully received.
Thanks
Theorist.

Example files below (test.lco and example.tex)

test.lco

\ProvidesFile{test.lco}[2005/07/14 letter class option]
\usepackage{graphicx}
\usepackage[english]{babel}
\@setplength{refvpos}{85mm}
\@setplength{toaddrindent}{6.5mm}
\setkomavar{fromaddress}{1 My Road,\\
My Town,\\
My County.\\
Post~Code}
\setkomavar{fromphone}{0123 456 7890}
\setkomavar*{fromphone}{Tel.:~}
\setkomavar{fromlogo}{}
\setkomavar{backaddress}{}

example.tex

\documentclass[fromalign=right,BCOR=0pt, DIV=12,
test,fromphone=true,
fromlogo=true,
paper=a4,
parskip=full,
fontsize=12pt,
foldmarks=true,
subject=afteropening
]{scrlttr2}
\date{Wednesday 14${\rm ^{th}}$ December 2005}
\setkomavar{subject}{Why such a big space?}

\begin{document}
\begin{letter}{Mr Smith,\\
1 Smith Street,\\
His Town,\\
His City,\\
Post~code.
}
\opening{Dear Agent Smith,}
Why is there such a big space between this line and the subject line
above. Nothing I do seems to be able to shrink it down or place the
subject in the middle of the area between the opening and this paragraph.
\closing{Yours sincerely,}

Theorist.
\end{letter}
\end{document}