Dear Simon,
The John Wickham and Elizabeth Furling in question are a bit "too new" for my study period, but I can share a couple tidbits where records mention the family prior, including your Philip from Ballygillane.
The first family reference are those interned at St. Ruane Cemetery. This is the original i.e. OLD cemetery in Kilrane and most likely spot for Catholic internments in the late 18th to mid 19th century. There are a smaller number late 19th to 20th century interments here but you are right, the place was pretty full by then and many went to St. Aidan's unless the family still had room at St. Ruane. One of these men may be Philip's Grandfather? As mentioned, they are interned directly next to (to the left) of my O'Connor ancestors interned here from Ballygeary. Ballygeary directly borders Ballygillane so they knew each other. i.e. were neighbors.
Here is a preview of those interned noted: (Photo)
In 1833, Tithe records show the head of household for the Wickham farm in Ballygillane as James Wickham. If Philip was from Ballygillane this is a relation; likely either father or brother (??)
The farm was 20 plantation acres, and near the Patrick FURLONG farm in Ballygillane which was also 20 plantation acres.
The first mention of a Philip I have on file is found in Subscriptions to the Poor Relief Fund in the Electoral Division of Roslare, in the Poor Law Union of Wexford July 28 1846 when he made a contribution of 1lb 1 shilling to the famine relief effort.
1848, another mention of him, this time contributing to the Daniel O'Connell "Repeal Fund" (Freeman’s Journal: 2 May 1848)
By the 1850's Griffith's Valuation something interesting happens. James Wickham (spelled Weekin) is still head of household for the farm in Ballygillane Little, tenant farmer on property owned by ? Watts. John Furlong has replaced Patrick Furlong as head of household in the same township, and is also a tenant of ? Watts. However, we now see a Philip Wickham (again, Weekin) as head of household of the Wickham farm in Churchtown, a farm that is listed as 20 acres, and in 1833 belonged to a Henry Wickham. Tenant farmer of Eliza C. Edwards, one of the larger Lessor's of property in that era. There was a Furlong farm on Churchtown as well.
I hope this is helpful!
Best, Deb N.