A friend of mine is a firefighter, and it took 3 attempts before he was sucessful. Its has been said that the service want to see how dedicated and serious an applicant is, so if your partner is not successful first time, dont lose heart, as applying again will show his committment.
In the meantime, it is crucial for your partner to highlight certain things. Valuing diversity is one, the service place great emphasis on social awareness with regards ethnic communities, for example.
Also, many firefighters have found themselves in hugely volatile situations where for some reason, people have been incredibly violent and aggressive towards them. Your partner must show that he can handle community relations and difficult situations with tact, diplomacy, empathy, and rationality (and you can also translate this into his ability to assess a situation and the actions required in a fire situation where he needs to be levelheaded and on the ball)
The service need you to be very fit and resiliant, its crucial to be a team player and understand your role within that team, they want to hear an applicant is ambitious and open to continual training, assessment etc. Many fire fighters try to get out of community work (like going round thier area fitting fire alarms for free and raising awareness of fire safety) so if your partner shows dedication and a genuine openess to all aspects of the job, this will look very good.
Im sure there is loads more Im missing so will ask my mate and get back to you x