He is chiefly known by his pseudonym of Old Humphrey, under which name he published 46 works, but also used the pen-names "Jeremy Jaunt", "Ephraim Holding", "Peter Parley" and "Old Father Thames".

His friend and biographer, Charles Williams, noted that George, as a child, was 'taught to occupy and amuse himself', a trait which led him, unattended, to explore a local building site, where he suffered severe injuries falling into the newly dug foundations, leaving him with a scar on his forehead which he would bear for the rest of his life.

Years later, Queen Victoria, flattered by poems Mogridge had written in celebration of her and her husband, Prince Albert, agreed to contribute to this pension.

[2] Mogridge was already a well-known and prolific writer by 1833, when he chose the pseudonym "Old Humphrey" for his authorship of a series of children's books for the Religious Tract Society.

Two biographies of his life appeared shortly after his death, one, particularly florid and exuberant, written by his close friend Charles Williams,[2] the other sponsored by The Religious Tract Society.

Later, during his apprenticeship years, he made the acquaintance of Samuel Jackson Pratt, a prolific and popular (though now largely forgotten) poet who lived in Colmore Row, Birmingham.

The early columns dealt principally with the need for improvements to Birmingham, but in later years also tackled more widespread subjects including expressing support for the anti-slavery movement.

The ballad told the tale of a poor, drunken, miserable man who is brought to realise that his poverty and misery are due to his neglecting to attend church on Sundays.

In response Mogridge began to imbue his pseudonym with the character of an elderly, kind hearted gentleman, responding to one paper's article, "Who is Old Humphrey?"

with an enigmatic description beginning, If you see an elderly-looking man parting two passionate boys who are fighting; giving twopence to a poor girl who has by accident broken her jug, to make all right again; picking up a fallen child out of the dirt; guiding a blind man carefully across the street; or hesitating for a moment if an importunate beggar is an imposter or not and then deciding in his favour; if you see such a one, so occupied, he is not unlikely to be Old Humphrey.

Mogridge used various other pseudonyms, both male and female, in his long career, including "Uncle Adam", "Old Alan Gray", "Ephraim Holding", "Uncle Newbury", "Aunt Newbury", "Old Father Thames," "Grandfather Gregory", "Grandmamma Gilbert", "Aunt Upton", "Amos Armfield", "Godfrey Gilbert" and "Peter Parley" – the latter bringing him into conflict with an American writer, Samuel Griswold Goodrich, who also wrote under that name.