When you are looking for your Gash ancestors please try Gaish as well I have two Great Uncles who were registered as Gash instead of Gaish in error I have found another family with sons who have surnames of Gash and Gaish in Halling in Kent.
See my Gaish family trees on this site it may help. oh yeh on the 1881 census one Gaish family is misspelt as Guish so Gash could end up as Gush as well.
If you have a Walter James Gash born 1862 he may be my Gt Grandad Walter James GAISH I am still looking for his birth.