Elsie and Herbert Pilkington were the 8th and 9th children of Henry Pilkington (1859-1923) and Mary Holden (1857-1917) of Darwen.
Herbert was born twentysomethingth of Mar 1899 and baptised at Darwen St Cuthbert 11 Oct 1899.
Elsie was born 18 Aug 1895 and baptised at St Cuthbert's 11 Sep 1895.
On the 1901 and 1911 censuses they are living with their parents and siblings at 15 Bright Street, Darwen.
It looks like Elsie married Joseph Cooper in 1919 (I've sent for that marriage certificate to confirm) and they had a son John Pilkington Cooper who was born and died Q1 1923.
Herbert was a witness at his brother, Ernest's marriage to Emma Hitchman 10 Sep 1921 in Darwen.
But I can't find a trace of either Elsie or Herbert after 1923/1921 respectively.
There is a death of an Elsie Cooper in Darwen in 1962, but this is not her, as the Pleasington burial register shows that Elsie Cooper to be the wife of a Herbert Cooper.
If they were still in England in 1939, their entries on the Register must be concealed by mistranscription, probably of their birth years.
Can any kind rootschatter spot their deaths or emigration, or whatever else might have happened to Herbert, or to Elsie and her husband?
