Hi Julie, I have in my tree, William Maxam b. 1802 Foxearth. Married Hannah Harding 8 April 1826, they have 9 children, all born St. Pancras.
I have over 100 Maxams, all descendants of William.
I understand William's surname was most probably Maxim, but because of his strong accent, London people spelt it Maxam, and that the way it's stayed.
Get in touch if I can help.
Derek