His antiquarian interests also included armour. In 1834 he published "A Catalogue of the Collection of Ancient Arms and Armour, the property of Bernard Brocas, with a prefatory notice". In 1857 Planché was invited to arrange the collection of armour formerly belonging to his friend Sir Samuel Meyrick for the Art Treasures Exhibition in Manchester, a task which he repeated in South Kensington in 1868. Concerned by the state of the armour in the Tower of London, Planché wrote several reports on the subject between 1855 and 1869. In that year, the War Office invited him to rearrange the collection in chronological order, which was one of the things for which he had been campaigning.