I have the during the weekend been fact checking a book manuscript with focus on the Swedish navy. In the course of that work I happened to take an interest in the shipbuilder Francis Sheldon, who according to the article in Svenskt Biografiskt Lexikon by Jan Glete probably was born in the 1610's. This would seem to be very unlikely (if not outright impossible). Sheldon was more likely born somewhere around 1630 (possible slightly before) as the son of another Francis Sheldon, who in 1630 became Clerk of the Cheque at Woolwich. In the will of the latter, dated 1646, the son is described as being not yet 21 years of age and learning to become a shipwright. This means that when Sheldon arrived in Sweden inte late 1650's he was not in his 40's (as Glete believed), but a young man possibly not yet 30 years old.
Sheldon also turns up in the archive of the Livonian Governor General as he worked in Riga for some time. On 23 June 1683 the Admiralty asked Governor General Christer Horn to assist in an inquiry concerning some accusations against Sheldon.
LVVA. fond 7349, op. 1, vol. 167
London, National Archives, PROB 11/199/749