There are a few areas of pensions where it is currently still legal to treat men and women differently, (mainly related to the fact that women tend to live longer).
It is illegal to discriminate when:
It is legal to discriminate between men and women:
Sex discrimination has been made more difficult in recent years, largely thanks to European law and union action. But pensions built up before 1990 may still be treated differently. This is a complicated legal area, and you would need to take detailed advice.