I have an English wood type catalogue that states their wood type can be cut either curved or flat. How they locked together on the cylinder I do not know.

An eBay seller told me that:
"A rotary printing press is a printing press in which the images to be printed are curved around a cylinder. Substrates can be sheet feed or unwound on a continuous roll through the press to be printed and further modified if required (die cut, overprint varnish, embossing). These particular ones are 1930s and were for posters and billboards. The type that I have is about 6-9 inch high curved blocks that would fit a drum about 3 feet diameter. They came to prominence in the 1930s for a very, very  short while but never really 'caught on' in the UK and few blocks were made and were seldom used after WW2. Consequently the letters for them are usually in exceptionally good condition and are now very hard to get hold of. I do not currently know of a single Rotary Drum Press in the UK that is operational. Some do exist in Chile!!! After the war countries such as Chile bought a lot of the presses very cheap."

The catalogue page comes from an 1897 Day & Collins catalogue.