Some snippets:-
I have had a look at the Valuation Revision Books on the PRONI website , with regard to the townland of Ballyboley.
1866-1879 David Askin (house, forge, garden) valued at £1-15-00.
1880-1882 [remains same as above].
1883-1900 The 1893 alteration to valuation, with the name W J Edgar (my great grandfather) inserted, has gone up to £4-10-00 suggesting that a substantial alteration to the buildings has taken place.
1921-1930 The valuation change in this period is in 1929 and the name of the occupier has changed to Agnes Jane Edgar (nee Dornan) [my great grandmother]. William John Edgar died in 1927 and Agnes Jane Edgar in 1946.
What is known is that permission to remodel and extend the forge was granted on 18th August 1892.
This was done at a cost of £180 to be paid off @4% over a period of 35 years, ending in 1927.
William John Edgar (b 19-01-1857) was the first-born son of William Edgar (b c 1836) and Eliza Askin (b c 1839) [David Askin's daughter]. They went to North East England in the early 1860's (where William worked in the shipyards), leaving behind William John Edgar with grandparent David Askin in Ballyboley. Having lived with grandparent David Askin, William John inherited the premises.
There is a record of David Askin (b c 1806) (died 1887 - death registered in Newtownards). Could this be the David Askin in question? It may be the case, considering that the new forge was the undertaking of William John Edgar commencing in 1892.
Hope that the above may be of interest.