Sorry for the double post.
I have found a solution. I thought there would be a pre-built xslt function but there wasn't.
This is what I did - pretty basic but works for what I needed.
Code:
<!-- Converts 2008-03-21T00:00:00 to 21/03/2008 -->
<xsl:template name="format-date">
<xsl:param name="date" />
<xsl:param name="format" select="0" />
<xsl:if test="$date !=''">
<xsl:variable name="year" select="substring($date, 1, 4)" />
<xsl:variable name="month" select="substring($date, 6, 2)" />
<xsl:variable name="day" select="substring($date, 9, 2)" />
<xsl:value-of select="concat($day, '/', $month, '/', $year)" />
</xsl:if>
<xsl:if test="$date = ''">
<xsl:text>Not stated</xsl:text>
</xsl:if>
</xsl:template>
Tony