Evening all, I need to pick your brains if I may

I have the following family in 1901, living in Whitley Street, Manchester
Frederick Boulton Head Married Age 29 born 1872
Elizabeth Boulton Wife Married Age 27 born 1874
Harry Boulton Son, Age 7 born 1894
George Boulton Son, Age 5 born 1896
Frederick's birthplace is given as Australia, which I can tell you is nonsense! He was born in Gloucestershire. The others were born in Manchester.
Now I cannot for the life of me find them in 1911, and need some fresh eyes or ideas.
- I believe Frederick died in 1909, so he can be ignored for the purpose of this. The others should be there though.
- I have no reason to believe they moved away...I have references to George in Manchester up to the 1920s.
- Harry was actually William Henry
- I've tried various spelling variations in case of mistranscription without any joy.
Any suggestions please?