Thanks!!
Migration period and/or Viking age.....mmmm for England I guess both, for Northern Netherlands I guess mostly the Migration Period.
You must know there are two significant parts in the Northern Netherlands:
a. Inland, higher sandy territory ('Saxon') this part is fully integrated in the oldest population developments of Northwest Germany and Southern Scandinavia, so Ertebølle (Swifterbant), Funnelbeaker, Corded Ware, Bell Beaker, Nordic Bronze Age. The last on could be interesting because about 1600 BC there was a heavy influence of the Nordics, see this, with the magnificent title, 'the end of the Nordic rainbow'
http://rjh.ub.rug.nl/Palaeohistoria/article/view/25026
But I guess reading your posting 1600 BC is to early for a N1c influence from the NE to the NW?
b. Coastal, wetland territory ('Frisian') people inhabited these areas about 500 BC, at the end of the Roman period, about 3/4 th century AD a severe population decline, followed by a very clear influx of the Nordics, the Saxons (from Nordalbingia), Angels, Jutes. Could this populations/tribes at that time (4th/5th century AD) from the Northsea side of Germany and Denmark already be influenced by the N1c from the Eastsea?
The old anthroplogist suspect 'East Baltic' phenotype features along this tribes. But could be projection.