Possibly. The European Court of Justice has ruled that in some circumstances employees may reasonably claim that there are 'serious doubts' about the benefits brought to their employers by longer service, and that, where such doubts are justifiable, the employer who uses longer service to justify better pay for one sex than the other, may be required to prove specific justification (see question nine, above). The mere fact that one sex generally works longer than the other would not be enough.
You might, in any case, fall foul of the new legislation on age discrimination. Service requirements of up to five years are exempted, but you might have to demonstrate a business advantage if you intend to require service in excess of five years to obtain better benefits.
