With reference to this earlier post regarding the younger brother of my late father Ronald JACKLIN 1922-2006:

A recent search of FreeBMD reveals the death of one Wilfred JACKLIN 1926-1926 age 0. In fact Wilfred JACKLIN's birth and death are both registered in December 1926 which would account for my father having little recollection of his younger brother.

I did anticipate this would probably be the case so I held back from ordering the birth certificate. I will now request the birth and death certificates from Sheffield Register Office.