Alfred marrying under that surname the following year. Interestingly Charles never acknowledges in the Will that the brothers are his sons. They are always referred to as "the sons of Charlotte Kearvell" as can be seen in the Will exerpt below:
"......To Alfred Cheesman Kearvell another son of
the aforesaid Charlotte Kearvell....."
Charlotte herself is only referred to in the Will as "residing with me" as can be seen in the following exerpt:
"... for the payment of an annuity or clear yearly sum of one
hundred pounds to Charlotte Kearvell now residing with me during her life...."
She is left an annual annuity of £100 with the strict proviso that she must not anticipate the funds in any way otherwise the annuity will cease! Nowhere in the Will is any mention of Charlotte being his wife. There are no references to a wife's dower and rights of thirds and freebench that would have signified a marriage.
After Charles's death
In the 1851 Census Charlotte is living alone, by "Independant/Annuitant” means, in Bosham with one servant. Her surname is given as Kearvell. By the 1861/1871 Census Returns Charlotte is living at Rectory House, Bosham with her son, Alfred, who is now both a Farmer and Coroner and Chamberlain for the hundred of the Manor of Bosham. Charlotte is shown as living by "Independent/Annuitant" means, she gives her surname as Cheesman and signifies that she is a "widow". Well at least one of those statements was true!
There is little hard evidence between 1813 (the birth of their first son) and 1841 ( the Census Return) of the status between Charlotte and Charles and we can only speculate and wonder how and why their relationship developed. We must remember that this was the Georgian era when men and women enjoyed a robust attitude towards sex and positively relished breaking the rules set by their puritan forebears. There was an acceptance that sex was an inevitable and necessary part of life. This was an era of the rising power amongst the middle classes and preceded the prudery of the Victorians. Perhaps like the 'common-law' partnerships with which we are very familiar in the 21st century.
One final twist to the Cheesman-Kearvells to leave you with. Roger Cheesman was married twice. The second time (as a Cheesman) in 1853 to Mary Ann Halstead the sister of Alfred Cheesman's wife, Caroline Louisa Halstead. Roger died in November 1886 and exactly a week later Alfred took his own life with a shotgun…… now therein must lie another story!

Update March 2008 :- An extract from the Hampshire Telegraph and Sussex Chronicle
Newspaper for December 1886, about the suicide of Alfred, gives the probable reason.
“Mr Cheesman, who was well known in this district, had of late been depressed in
spirits owing to an affection of the eyes (Cataracts?), which threatened to deprive
him of his sight, and a few days since he experienced a loss in the death of his
brother”.