Other information I have (all from a diary of a trip back to England after 41 years) is that Mary married William Haigh and had a daughter Violet - who may have migrated to Australia, but at least worked here for some time, a son Douglas who was a carpenter. Sarah was Mrs E JOnes and John met her daughter and 2 g-daughters - no names given but she lived in Heswall. He visited Williams grave at Laudican Cemetry. He visited his brother George in Liscard , who was being looked after by daughter Betty.
He aslo mentioned seeing the grave of Aunt Johanna at Flaybrick cemetry (where his parents are buried) who died in 1951.
I don't know how far you are taking the off shoots of the family tree, but if you wanted information on the decendents of John Percy let me know.
Does a Dave come up at all? We have a photos marked to Uncle John from Dave. As he did not keep in touch with the family of his late wife, we can only presume it was the son of one of Johns siblings.