The minute books and other items are kept in the London Metropolitan Archive . The archive is open to the public and free to visit. Most of the information relating to Sir John Cass and his school belongs to the Cass Foundation, and the trustees have agreed that the majority of it should be kept in the London Metropolitan Archive for safety and so that anyone may see it.
Some of the information is in other places – the British Library has the biggest collection of old newspapers in the country, and they have copies of the papers that include reports about Cass’s career and some of the developments at the school.
At the National Archives at Kew there are more minute books – this time for the Royal Africa Company. These contain details of the meetings Sir John Cass went to when he was helping to run that company and the letters he and his colleagues signed giving instructions to captains of slave ships.
The Guildhall Museum has an extensive collection of pictures of London throughout the last three centuries: some of the early pictures of the school buildings and the surrounding area are to be found there.
The Hackney Archive has pictures of the area and other properties all around the Cass house in Hackney, but sadly, none of the house itself
The cartoon of Sir John Cass is kept in the British Museum.