I'm wondering if this could be Hugh on the 1901 England census in Barrow in Furness, Lancashire:
Hugh Groundwater, head, 43, mechanical engineer, born Ireland
Mary I Groundwater, wife, 36, born Workington, Cumberland
Atholl H Groundwater, son, 9 months, born Barrow in Furness, Lancashire
Jane Pears, mother-in-law, 69, born Workington, Cumberland
Francis Harvey, boarder, 48, carter, born Ireland
Mary A Brocklebank, boarder, 45, hawker, born Ireland
(Piece: 4011; Folio: 101; Page: 29)
There is a marriage for Hugh Groundwater that has a Mary Isabella Pears on the same page in the FreeBMD that was registered in second quarter of 1898 in Barrow in Furness, Cumbria, Lancashire (Volume: 8e, Page: 1600) and a death for Hugh Groundwater, 59, that was registered in the third quarter of 1913 in Barrow in Furness, Cumbria, Lancashire (Volume: 8e, Page: 922).
It looks like Athol died shortly after the census was taken as his death was registered as follows:
Athol Maud Groundwater, under 1 year, second quarter of 1901 in Barrow in Furness, Cumbria, Lancashire (Volume: 8e, Page: 565).
The 1911 England census has the family as follows:
27 Arthur Street, Barrow in Furness, Lancashire
Hugh Groundwater, head, 49, general labourer, born Banjor, Ireland
Mary I Groundwater, wife, 45, born Workington, Cumberland
Mabel Groundwater, daughter, 9, born Barrow in Furness, Lancashire
Annie Groundwater, daughter, 6, born Barrow in Furness, Lancashire
Jacquie