Still no trace of Sarah!
I've found a huge amount of records for her husband John, but no sign of Sarah nor their son.
Her husband John Patrick Irwin emigrates to the USA in 1909. He is strangely NOT recorded as being widowed, when he remarries in 1911. He remains in the USA until his death in 1958.
Sarah last appears in 1906, on their son's birth record. Their address was 64 Warleigh Avenue, Devonport, England. There's no trace of Sarah and their son after this date.
Husband John re-appears in 1908, living back in his hometown Queenstown, Cork, Ireland.
Where were they in 1906-07 and did Sarah and their son pass away during this time? Perhaps I'm looking for death records, in countries that do not have their records online? Or perhaps Sarah left John and took on another surname?
If anyone finds mention of Sarah Marion Irwin nee Staples (born 27 Dec 1882), or son John Arthur William Irwin (19 Jun 1906), please let me know!
(I've traced all of Sarah's siblings and she doesn't appear in any records with them, and is not mentioned in their Wills)
