I'm pretty sure from the 1881 and 1901 census returns, that Alfred was born during q1/1852 in the district of Shoreditch, London.
__________

Agnes Louisa married Alfred Edward Matthews in Holborn District, London, Middlesex, England in q4/1872, and they can be seen living at 13 Berger Road, London, Middlesex at the 1881 census return:
Alfred MATHEWS Head Male 29 Kingsland, Middlesex Clicker (Boot)
Agnes MATHEWS Wife Female 29 Paddington, Middlesex
Agnes MATHEWS Daur Female 8 Homerton, Middlesex Scholar
Alfred MATHEWS Son Male 6 Homerton, Middlesex Scholar
Herbert MATHEWS Son Male 5 Homerton, Middlesex Scholar
Harry MATHEWS Son Male 2 Homerton, Middlesex
William MATHEWS Son Male 1 Homerton, Middlesex
Henry MATHEWS Lodger Male 33 Shoreditch, Middlesex Shoe Maker
__________

We also see Alfred and Agnes in 1891, living at Copland Farm, Hackney, London:
Alfred E Matthews Head 39 Clicker London Shoreditch
Agnes L Matthews Wife 39 London Whitechapel
Harry Matthews Brother 42 Boot Lacer(?) London Shoreditch
Walter Matthews Brother 35 Boot Finisher London Hackney
Alfred Matthews Son 16 Assistant to Dryers & Cleaners London Honnerton
Herbert Matthews Son 15 Clicker London Hackney
Harry Matthews Son 12 Scholar London Hackney
William Matthews Son 11 Scholar London Hackney
Frank Matthews Son 9 Scholar London Hackney
Edwin Matthews Son 8 Scholar London Hackney
Horace Matthews Son 5 Scholar London Hackney
Florance Matthews Daur 2 London Hackney
Alice Matthews Daur 9 mnths Hackney London
__________

Agnes and Alfred can also be seen in 1901 living at Hackney, London, Middlesex.
Alfred E Matthews 49 London Hoxton London Hackney Bath Attendent
Agnes L Matthews 49 London Whitechapil London Hackney
Alfred Matthews 26 London Homerton House Paint Decorator
Herbert Matthews 25 London Homerton Boot Clicker
William Matthews 21 London Homerton Engineering Labourer
Frank Matthews 19 London Homerton ?? Labourer
Edwin Matthews 18 London Homerton Confectionery Porter
Horace Matthews 16 London Hometon Medicine Packer
Florence Matthews 13 London Hackney
Maud Matthews 10 London Hackney
Frederick Matthews 8 London Hackney
Jane Mills 26 Boarder London Paddington

Agnes' father, Henry Theodore Knibbs isn't strictly a member of the Knibbs family. His parents were John and Ann BURT so his real name is Henry Theodore BURT. Henry's mother was widowed and then married Francis Knibbs (1793-1856).
Henry married as Henry Theodore BURT but at a later date, he assumed the surname KNIBBS.
__________

We see Agnes in 1911, a widow, living at 43 Harrogate Road, South Hackney, London:
Agnes Matthews Head Widow F 59 London St Georges
Henry Matthews Son Single M 32 Fitters Labourer London Hackney
William Matthews Son Single M 31 Pipe Fitter London Hackney
Edwin Matthews Son Single M 27 Bus Conductor Motor London Hackney
Horace Matthews Son Single M 25 Barman London Hackney
Florence Matthews Daughter Single F 23 Milliner Childrens London Hackney
Alice Maud Matthews Single F 20 Milliner Childrens London Hackney
Frederick Matthews Son Sincle M 18 Clerk London Hackney
Christina Matthews Grand Daughter Single F 6 London Hackney
Thomas Matthews Grandson M 4 London Hackney
James Matthews Grandson M 2 London Hackney
Arthur W Durrant Boarder Single M 24 Bus Driver Motor Greenwich Kent

I'm not sure who's children Christina, Thomas and James were.
Christina was in fact Christine Hilda Matthews, born in q2/1905 in Hackney District
James is probably James William Matthews, born q4/1908 in Hackney District