It's Bedfordshire's most important prehistoric earthwork. That's not saying much :-)
I don't have any pics, but here's a basic listing:
http://www.megalithic.co.uk/article.php?sid=1479
Looks like they found one:
I found this too - wow!
http://www.britac.ac.uk/news/reports/archaeology/maiden.html
More good stuff here
http://www.britac.ac.uk/news/reports/archaeology/asfa.html
Andy