Norinyl-1 is the only combined pill in the UK containing a completely different type of oestrogen called mestranol. Fun fact; the body changes mestranol into the same oestrogen found in standard pills like
Microgynon and
Rigevidon. The dose is roughly equivalent to a high oestrogen dose pill, but some women might find their side effects are better on Norinyl-1 as the oestrogen is different.