We had a couple of Dutch entrants on the Punchbowl Marathon at the weekend, who were very jolly and had a good time. Lots of photos, here
http://www.funrunner-heerlen.nl/funrunner-fotoserie-07/index.html

They are also their own 70km challenge walk/run in south Holland for next month - 20 March - and would be pleased to hear from anyone interested in venturing across the channel to give it a go. They recokoned it was similar going to the PBM, so moderately undulating rather than hilly.

The weblink is
http://www.funrunner-heerlen.nl/funrunnerlopen/index.html

Unfortunately (but not surprisingly) it's all in Dutch but they spoke very good English and would be able to reply to any e-mail enquiries in English.