I don't know if I emntioned it but I am wrtiting since 5 or 6 years a history of the Lovekyn to Lufkin family. I am currently writing the late 15th century and the original family in New England. I just came to the marriage of Thomas Lufkin to Sarah Downing. I was interested enough when it mentioned that she was descended from the Downings of Downing College and Downing Street.
So I embarked on a search with the following brief results.
Sir George Downing MP was the Secretary of the Treasuriy in England for a few years from 1667. He was also an entrepreneur and he laid out the plans for Downing Street. When it was built in or around 1680 it was named in his honour for his services to Parliament and the country.
His son Sir George Downing MP B 1685 d. 1749 bequeathed in his will an endowment to establish a College at his former university Cambridge. A proviso in his will that the bequeathment would only happen if his heirs and cousins died without issue and his branch of the family did not continue. After the deaths of his cousins other relatives contested the will and fought it in court for many years until it was finally turned down around 1800. After this the building of the College took place and was of course named after him. It is interesting he died without issue as did his heirs
What this means then is that Sarah could not have been directly descended from Sir George or his son but a more distant relative.
I hope this does not spoil things for someone.