Nathaniel's marriage to Jane/Joan/Joanna Overton on the date of 7 March 1670/1 is recorded in the parish register of Little Casterton, Rutland. As: "Nathaniell Johnson Esq: and Mrs. Jane Overton were married March: 7th 1670". Also, in the Proceedings of the Society of Antiquaries of Newcastle upon Tyne, 3rd Series, Vol. 9 (1919-1920), page 161, under "Lamesley" in the article on 'the Coleman Deeds', there is notation of a post-nuptial property settlement as follows:
"1671, Aug. 30. Settlement after marriage of Nathaniell Johnson (elder son of William Johnson) and Joanna, his now wife, daughter of Robert Overton, between (1) William Johnson of Kibblesworth, merchant; (2) Sir Thomas Liddell of Ravensworth castle, bt., John Clarke of Newcastle, esq., Robert Overton of Easington, co. York, and Andrew Broughton of Seaton, co. Rutland, esq.; and (3) William Dawson of London, gent., and John Carr of Newcastle, merchant. Manor of Kibblesworth."
Here is a link to the article online: http://babel.hathitrust.org/cgi/pt?id=hvd.32044090394941;view=1up;seq=203
There are many references to Andrew Broughton being wed to Ann / Anne Overton. Perhaps the most direct comes from Robert Overton, Esquire's will dated 23 June 1678 and proved 29 Jan 1678/9 in which he makes reference to his son [no first name given] Broughton and his wife, Mrs. Anne Brougton. [PCC 8 King (1679), folio 64].
I have done substantial research on the Broughton, Overton, and Johnson families, and am hoping eventually to add what I can to the relevant profiles.