Grouping by key

Hello,

I have XML document like below.  I am trying to present the data 
categorised by say for eg. town like as in expected output section.  I am 
not getting the expected output when using the xsl file as given below.  I 
am obviously missing something.  Can somebody correct me to get the above 
output.

Many thanks.

XML Docment:

<documents>
<account>
<accountnumber>0001></accountnumber>
<companyname>ABC Ltd</companyname>
<town>Ford</town>
<postcode>FD13QG</postcode>
</account>
<account>
<accountnumber>0002></accountnumber>
<companyname>XYZ Ltd</companyname>
<town>Ford</town>
<postcode>XY13QZ</postcode>
</account>
...
...
...
</documents>

Expected output: 

Ford
        0001    ABC Ltd FD13QG
        0002    XYZ Ltd         XY13QZ

 xsl file:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
          xmlns:msxsl="urn:schemas-microsoft-com:xslt"
  version="1.0">
  <xsl:output method="xml" omit-xml-declaration="yes"/>
  <xsl:key name="categorise" match="account" use="town" />

  <xsl:template match="/">
    <div> 
      <xsl:apply-templates select="documents" />
    </div>
  </xsl:template>

  <xsl:template match="documents">
    <table>
      <xsl:apply-templates select="account[generate-id() = generate-id( 
key( 'categorise', town ) )]" mode="catcols" />
    </table>
  </xsl:template>
 
  <xsl:template match="account" mode="catcols">
    <tr>
      <td><xsl:value-of select="town" /></td>
      <xsl:apply-templates select="//account[generate-id() = generate-id( 
key( 'categorise', town ) )]" mode="catrows" />
    </tr>
  </xsl:template>

  <xsl:template match="account" mode="catrows">
    <tr>
      <td><xsl:value-of select="accountnumber" /></td>
      <td><xsl:value-of select="companyname" /></td>
      <td><xsl:value-of select="postcode" /></td>
    </tr>
  </xsl:template>
</xsl:stylesheet>