I just had a look on the handprint
website, and they list two W&N magenta paints that I could see, both single pigment.
The first is quinacridone magenta (W&N 229) which is pigment PR122. The other is permanent magenta (W&N 073) which is PV19. As Patrick said, either of those should give reasonably clean reds when mixed with a yellow (assuming, of course, that the yellow is also a single pigment). To get a really strong red you probably want to go for a suitable single pigment red, but you should be able to get some pretty good reds out of magenta and a decent yellow (one of the more orange shades of yellow, like perhaps cadmium yellow, would do better than a green shade like lemon yellow, I expect).
Keep experimenting and let us know how you get on.