Thanks for all your input. Her timeline follows. If we look at her being born c.1862/1863 she would have been 47 when she had her last child. Not impossible but 3 children in her 40's in the early 1900's?
16 Aug 1881 Marriage to James Norman Harrison, soldier,
Pimlico St Peter
Minor (16), spinster, address Wallis Yard, Westminster
c.1882 Birth of Amelia J Harrison, Cork, Ireland
1883 Birth of Elizabeth Mary Harrison 4th qtr 1883 St Geo H Sq 1a 430 mmn: Locke
10 Jul 1885 Birth of Norman Harrison Spencer Buildings, Westminster mmn: Crummett
1887 Birth of Eliza Harrison 2nd qtr 1887 St Geo H Sq. 1a 44 mmn: Lock
1891 Birth of James Harrison 2nd qtr 1891 Wandsworth 1d 616 mmn: Locke
1893 Birth of Agnes Harrison 4th qtr 1893 Wandsworth 1d 549 mmn: Locke
1895 Birth of Grace Harrison 4th qtr 1895 Wandsworth 1d 552 mmn: Locke
1897 Birth of Richard Harrison 3rd qtr 1897 Wandsworth 1d 608 mmn: Locke
1901 Death of husband (James Norman Harrison) 3rd qtr 1901 Wandsworth 1d 322
1905 Birth of Arthur William Addison 1st qtr 1905 Wandsworth 1d 565 mmn: Locke
1905 Marriage 2nd qtr 1905 Wandsworth 1d 1255 to Arthur Edward Addison
1907 Birth of Ruby Helen Addison 1st qtr 1907 Wandsworth 1d 522 mmn: Harrison
1909 Birth of Philip Gressley Addision 2nd qtr 1909 Kingston 2a 462 mmn: Locke
19th Dec 1912 Emigration New Zealand ("Kemura" NZ Shipping Com. Ltd accompanied by husband and 3 Addison children/no Harrison children
17 Sept 1951 Death Auckland, New Zealand, aged 86 years
24th May 1969 Death of husband (Arthur Edward Addison) Point Chevalier, New Zealand