Aerssens was sent to London to smooth over the matter.

He had no easy task, but by skill and patience he contrived, in spite of many adverse influences at the court, so to allay the bitter feelings that had been aroused by "the scandal of the Downs" that Charles and his queen were willing, in the early months of 1640, to discuss seriously the project of a marriage between the stadholder's only son and one of the English princesses.

In January a special envoy, Jan van der Kerkoven, lord of Heenvlict, joined Aerssens with a formal proposal for the hand of the princess royal; and after somewhat difficult negotiations the marriage was at length satisfactorily arranged.

The ceremony took place in London, May 12, 1641.

As William was but fifteen years of age and Mary, the princess royal, only nine, the bridegroom returned to Holland alone, leaving the child-bride for a time at Whitehall with her parents.