Thank you Edmund for the information you supplied. It has proved to be very useful. I have forwarded it to the researcher and received this reply
" As it stands I still don't know which Joseph made the knife and probably never will although Joseph born 1846 seems the more probable due to him having a more established business.
I have attached the research I did some time ago on the two men, initially my main aim was to try and find out how old the knife was. I originally thought my dad had acquired the knife whilst in the RAF in the mid 1940's.However, I have concluded that it is much earlier than that and so now I feel my dad must have been given it by someone or inherited it.
1st Joseph Born in 1862
His father George was listed a Spring Knife Grinder or a Pen and Pocket Blade Grinder, George died in 1880 when Joseph was aged 18
In 1881 Joseph was listed as aged 19 and a Pocket Blade Grinder the same as his father
In 1885 Joseph enlisted into the army, he joined the York’s and Lancs. Regiment and was stated as being a Pen and Blade Finisher.
Joseph spent 12 years in the army including a spell in Nova Scotia, West Indies and South Africa, In 1897 Joseph returned to live with his widowed mother in Sheffield and had a short spell as a road labourer working for the local Corporation
By 1911 Joseph was listed as a retired Pen and Pocket Knife Finisher even though he was only 49
Joseph never married and died in 1921 aged 59
Conclusion: If Joseph No1 made the knife, it has to predate 1921 and could well be a lot older dating as far back as the early 1880,s
2nd Joseph Born in 1846
Father Isaac was a Table Knife Cutler who died in 1857 when Joseph was aged 13.
In 1861 aged 14 Joseph was listed as a Spring Knife Cutler.
In 1866 Joseph got married and by 1881 he and his family were living in Bramall Lane, Sheffield, again occupation was a Spring Knife Cutler
In 1884 Joseph was brought before Magistrates for threatening his wife and attempting to set fire to some furniture, he was fined and had to keep the peace for 6 months.
Joseph continued to be listed as a Cutler in censuses and directories at various addresses in Sheffield.
By 1911 Joseph was aged 64 and lodging with a family, no sign of his wife although still listed as married
Inclined to believe he was perhaps estranged.
Joseph died in 1930 aged 83; he left a will leaving £9378 (lot of money) to a firm of knife manufacturers Joseph Alfred and Francis Blackwell
Conclusion If Joseph No 2 made the knife then it dates before 1930 but could go back as far as the 1860’s.