The first talking books came on long-playing records - a technology pioneered by the RNIB and later adopted by the music industry.
The old MKI talking book player was replaced by the MKIV in 1965. Because the RNIB could not provide enough Mark IV players for everyone, an adapter was fitted to the old machines so that they could play the new, smaller cassettes.
In the 1940s talking books on vinyl discs were returned to the warehouse in hard, protective boxes. Before they could be sent to the next customer, each LP had to be carefully checked for scratches and cleaned of any fingerprints.
Postage was eventually free of charge under the Royal Mail's Articles for the Blind concession scheme. But the old cassettes were too bulky to go into a post box.
The RNIB eventually had three studio suites at its old Great Portland Street headquarters. Engineers would record two books simultaneously.
The multi-track cassette player had a lot of moving parts and needed regular servicing.
The latest digital players are light and portable - making it possible to read anywhere.