Here are some unlinked Gammon(s) that need more investigative work to link them to other trees:

1. Christiana GAMMON, married Thomas SEDGE (SAGE) on the 13th October 1765, in Borden, Kent, England. This marriage is on the IGI (https://familysearch.org/), but no parents are listed to help take the family further back in time. We really need a copy of the parish register entry for the marriage in Borden to see if there is any more information. Jenny Bradley is the contact who thinks that Thomas and Christiana were her gggg-grandparents. Update 28/4/2013 - FindMyPast have added records from the Kent Family History Society to their website. Unfortunately, these do not list any parents either. The only new information is that the bride is "of this Parish", and the groom resides in Hucking.

2. From an announcement in the North Devon Journal (18th July 2013):
GAMMON Mary Bubbles Formerly of Ilfracombe, aged 96. Loved by all her family, will be sadly missed. Thanksgiving service at St. Philips & St James Church, Ilfracombe on Tuesday 23rd July at 1.45pm.
Firstly, my condolences to the family. As I am writing this, the thanksgiving ceremony is tomorrow. I was not able to find Mary in my Database, therefore I have posted this part of the notice in the hope that a member of her family might be curious about her family history and get in touch.

3. Contact from David Gammon (27 December 2013):
John GAMMON (born around 1733) moved to Nova Scotia, Canada around 1755. His wife is either Frances or Lucy (born around 1737). David also has information about Gammon families in Maine and New Hampshire in the USA.

4. Contact from James Gammin (9 January 2014):
Believes that himself and his brother may be the only Gammin's left! He is from Devon.