There are a number of instances of the JOHNSON name in the tree. This portion of the website covers the JOHNSONs of Necton, Norfolk, who somehow became the JACKSONs before 1911.
Louisa JOHNSON gave birth to 3 children in the 1890s. All 3 were registered in the name of JOHNSON, and none have fathers named on the certificates. I have not found Louisa in the 1891 census, and there is no sign of her or her children in 1901. Louisa's occupation was listed as a barmaid on the certificates, and her address was never the workhouse, so it appears she was able to support herself and the children.
I was put onto the name change by finding a reference to my Grandfather Geoffrey JACKSON as being 'also known as' Garcon Edric JOHNSON. A cousin independently also discovered the JOHNSON link by finding an Insurance Policy in the name of H E JOHNSON when his maiden aunt who he knew as Hilda Evelyn JACKSON died. Hilda and Geoffrey were siblings. It remains a mystery why they changed their names. It is possible that Louisa married a JACKSON, but I have never found any sign of it, even after extensive on line searches. That hardly seems a reason to have changed the names of the children as well. And in the case of my Grandfather his complete name, not just his Family name.
Geoffrey was in the Navy for 25 years and served in both world wars. His 2 sons, Ralph and Peter, served in the second. I am currently in the process of obtaining first Geoffrey's then Ralph's Navy records from the Veteran's UK site.
I am - naturally - still researching the family. As new information comes to hand I will update the database.