John Johnson declared that he was born on 30 June 1821in Denmark and he died in Penzance Cornwall on 12 August 1899. He later changed his birthplace to Penzance on Census forms.
I have a copy of his marriage certificate to Rosanna Burgess for 14 September 1843 on which his father is stated as being John Johnson.
I also have certificates for him being a sea Captain and Master Mariner but they are not a lot of good tracing his birthplace.
Amongst his children's names are Margaretha, Sophia, Frederich and John Henry which would all appear to be in keeping with the Danish link.
I have also found a John Johnson on a list of Alliens arriving in Hull from Hamburg on the 'Leipzig' on 31 July 1851.