You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <query-continue>
    <alltransclusions gatcontinue="Britain_&amp;_Europe|2355" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1378" ns="3" title="User talk:John Alistair Kühne" />
      <page pageid="1448" ns="0" title="2007-04-04" />
      <page pageid="1578" ns="0" title="2007-04-23" />
      <page pageid="2311" ns="0" title="Britain and Europe - web resources" />
      <page pageid="2312" ns="0" title="Latest developments concerning Britain and Europe" />
      <page pageid="2337" ns="0" title="European Free Trade Association (EFTA)" />
      <page pageid="2343" ns="0" title="Common Agricultural Policy (CAP)" />
      <page pageid="2345" ns="0" title="Exchange Rate Mechanism (ERM)" />
      <page pageid="2346" ns="0" title="Single European Act (1986)" />
      <page pageid="2354" ns="0" title="Useful literature on Britain and Europe" />
    </pages>
  </query>
</api>