The Hastings Museum acquired in 1947 a peepshow of St Leonards on Sea, numbered 947.43. This is full of interest, as it shows an unusual view of the seafront, looking west from the archway. The Museum very kindly let me have photos of it.
First we have the front, with a small hole of the actual peepshow. Next we have what it would look like without the hole. Finally we have what it looks like from above.
This long, wooden and heavy type was becoming old-fashioned by 1840. In the 1820s peepshows made of paper, which expanded and contracted like bellows, became popular. This made them cheap, compact and light.
The Victoria and Albert Museum has the same peepshow; it is they who date it to 1840. If you follow this link you can see the cover of the peepshow, which has details about the early history of the town. If you click on the image, you can navigate to a second image with a vivid portrayal of the town through the peephole itself.
Postscript, 8 February 2024. By chance I noticed that an archivist had added an extra detail to the Hastings Museum’s catalogue entry: Peepshow of the Marina, St. Leonards in 1840, made by Jane Wood, daughter of James Burton to raise money for the St. Leonards National School. Jane lived at North Lodge, Maze Hill. The national school was located in what is now a mosque in Mercatoria, and promoted an Anglican ethos in education.