In 2009 a number of Dutch runners took part in the event: the reasons for this are not entirely clear, but the absence of significant hills in Holland may be part of the explanation.

Erasmus Universiteit group on Calton Hill at the 2009 event.
In 2010 the connection became stronger, when two organised groups came over to the event. One was from the Zevenheuvelenloop club — a business group of runners associated with the long-standing 15km Zevenheuvelenloop (7 hills race) in Nijmegen, which takes place in November each year. The other group were from the Erasmus Universiteit in Rotterdam. About 15 Dutch runners took part — some in the Race and some in the Challenge.

2010: Henk Albers of the Seven Hills Club of Nijmegen presenting one of their special race sculptures to Alan Lawson (Edinburgh Seven Hills organiser). Martin Buitinck on left, Kees de Ruwe and Charles Passmore (party host) on the right.
On the evening before the event, an informal reception was held in Edinburgh, at the home of some of the event's helpers, and a special sculpture from the Zevenheuvelenloop club was presented to Edinburgh's Seven Hills Race.
The evening-before social gathering has continued each year since, being held several times at the Midmar Allotments, sometimes at small sports clubs, and sometimes in Edinburgh pubs or clubs. Other overseas runners also get invited, as do the event's key workers, and some special guests.

3 Dutch runners from the Zevenheuvelenloop club on Calton Hill after completing The Challenge
* * *
A trophy for 'Best Dutch Runner' was introduced in 2013, and it is keenly contested each year.

The leader of the Dutch group, Pascal den Hartog, wrote this blog about his experience of the 2019 race...
https://7hills2h.blogspot.com/2019/06/seven-hills-2019.html
* * * * *
In 2020 (covid), with no real race going to happen in Edinburgh, a virtual 7 Hills event was held in Rotterdam (small hills), with 35 runners taking part. This has now become an annual event: you can read all about it HERE
(some knowledge of Dutch is handy)
* * * * *