We used the Flemish edition of the topoguide 'GR 128 Frans-Vlaanderen' (French-Flanders), dating from 1995. The booklet describes the trail from Wissant up to Kemmel, and constitutes the first part of the complete GR 128 trail.
A long time has passed since, but nevertheless the booklet still is more then useful to keep you on the right track.  The changes we've noticed during our hikes have been indicated as good as possible on our maps, because at the time they still weren't documented on the website of the Flemish GR organisation, neither were they included on the maps of the French IGN organisation.

The map below shows an overview of all the hikes we made on this part of the GR 128 trail. Links to the individual reports on each hike can be found below the map.