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>
    <allimages aistart="2016-09-06T11:08:04Z" />
  </query-continue>
  <query>
    <allimages>
      <img name="At_sign.png" timestamp="2022-04-22T13:31:00Z" user="Gerard Hand 5177b94160" url="https://www.gridpp.ac.uk/w/images/3/32/At_sign.png" descriptionurl="https://www.gridpp.ac.uk/wiki/File:At_sign.png" ns="6" title="File:At sign.png" />
      <img name="VomsSnooper_class.png" timestamp="2022-03-09T14:59:08Z" user="Gerard Hand 5177b94160" url="https://www.gridpp.ac.uk/w/images/b/bf/VomsSnooper_class.png" descriptionurl="https://www.gridpp.ac.uk/wiki/File:VomsSnooper_class.png" ns="6" title="File:VomsSnooper class.png" />
      <img name="VomsSnooper.gif" timestamp="2022-03-09T14:51:26Z" user="Gerard Hand 5177b94160" url="https://www.gridpp.ac.uk/w/images/6/6e/VomsSnooper.gif" descriptionurl="https://www.gridpp.ac.uk/wiki/File:VomsSnooper.gif" ns="6" title="File:VomsSnooper.gif" />
      <img name="LHCb_ECHO.PNG" timestamp="2019-04-24T07:21:51Z" user="Darren Moore 213b9e8222" url="https://www.gridpp.ac.uk/w/images/d/d7/LHCb_ECHO.PNG" descriptionurl="https://www.gridpp.ac.uk/wiki/File:LHCb_ECHO.PNG" ns="6" title="File:LHCb ECHO.PNG" />
      <img name="Hack_santa.jpg" timestamp="2018-12-18T11:03:25Z" user="Darren Moore 213b9e8222" url="https://www.gridpp.ac.uk/w/images/d/d4/Hack_santa.jpg" descriptionurl="https://www.gridpp.ac.uk/wiki/File:Hack_santa.jpg" ns="6" title="File:Hack santa.jpg" />
      <img name="Echoplot.png" timestamp="2018-11-20T09:26:56Z" user="Darren Moore 213b9e8222" url="https://www.gridpp.ac.uk/w/images/f/fb/Echoplot.png" descriptionurl="https://www.gridpp.ac.uk/wiki/File:Echoplot.png" ns="6" title="File:Echoplot.png" />
      <img name="Drv_fails.jpeg" timestamp="2018-03-05T15:58:05Z" user="Darren Moore 213b9e8222" url="https://www.gridpp.ac.uk/w/images/4/47/Drv_fails.jpeg" descriptionurl="https://www.gridpp.ac.uk/wiki/File:Drv_fails.jpeg" ns="6" title="File:Drv fails.jpeg" />
      <img name="Santa.png" timestamp="2017-12-20T11:09:54Z" user="Darren Moore 213b9e8222" url="https://www.gridpp.ac.uk/w/images/5/5b/Santa.png" descriptionurl="https://www.gridpp.ac.uk/wiki/File:Santa.png" ns="6" title="File:Santa.png" />
      <img name="Figure7.jpg" timestamp="2016-09-06T11:16:47Z" user="Stephen Jones 792bdf5225" url="https://www.gridpp.ac.uk/w/images/9/90/Figure7.jpg" descriptionurl="https://www.gridpp.ac.uk/wiki/File:Figure7.jpg" ns="6" title="File:Figure7.jpg" />
      <img name="Figure6.jpg" timestamp="2016-09-06T11:12:52Z" user="Stephen Jones 792bdf5225" url="https://www.gridpp.ac.uk/w/images/0/05/Figure6.jpg" descriptionurl="https://www.gridpp.ac.uk/wiki/File:Figure6.jpg" ns="6" title="File:Figure6.jpg" />
    </allimages>
  </query>
</api>