I have been reading old Gelling messages and wondered if the age of John Gelling who married Catherine Killey in 1739 has been cleared up yet (I have not checked every message).
If his father is the John Gelling who died in 1737, it states in that will (transcribed in BLs wills online) under the witnesses' marks:"The Execu'rx Sworn in Court in form of Law and Consents to give her part of the Crop to the Heir after her Decease, who being now present & AT FULL YEARS is Sworn Overseer....." This is on the same page as the will, it appears.
The will also mentions his two daughters Margaret & Elizabeth (names which are both mentioned in the will of Ann Gelling als Moor in 1748 as her daughters) and on the second of the "new pages" it states "Ann Gelling relict and Exec'tx of John Gelling..."
Just thought it might be of some help (or not!).