In reply to Scotch Bingington:
Bare in mind also, the fact that putting things like age, sex gender or race or indeed many other protected characteristics is not necessarily discrimination. It is perfectly OK for example to advertise for dark skinned actor to play dark skinned roles in films.
The general principle to avoid discrimination is to avoid using terms which directly or indirectly discriminate against those who are protected under law.
For example you cannot state males only, or no females, if you were advertising for an employee to work as a scaffolder for example. Nor should you state things which might discriminate, such as : "Strong person/s" wanted. It is however perfectly acceptable to state simple facts such as "Must be able to lift metal tubing which weights up to and including 22kg", because that is a genuine occupational need.