Thanks for your reply. I have only just seen your post (Ancestry didn't notify me of your response as they should have done).
I am looking for an immigrant called Hendrik van Essenhoogh, who would possibly have entered England somewhere in the mid-1700s, we think. It is thought he was born c.1723. He was certainly in Canterbury, England by 1740s. He came to the Kent area, possibly either via London, or perhaps Sandwich. I do not have any further details for him prior to his settling in this country, and was hoping ship immigration documents may have shed more light. Can you tell me where the early newspaper records are of ships leaving the Marsdiep? I will certainly try the British Admiralty records if I can.