Sunday School originated in Gloucester during the 18th century. Robert Raikes opened a place for kids working in factories, who had only Sunday off. He kept them engaged by teaching them to read & write, so that they do not commit crimes or mischief during the factory off-days. That's how the first Sunday school started in 1780 !.
St. Marks' Sundays School journey started 200 years back when the Church was built.