Why even highlight it was a "lone female" who was attacked? She is a person, her gender is irrelevant.
I think it is relevant when they are appealing for information. The police sometimes include descriptions of the criminals to help with such appeals for information. For example was the attack by one or more individuals and were the attacker(s) male, female, or other distinguishing characteristics. Apparently no such information has been included in this 'appeal'.
I Googled this particular advice and it does not seem to be common advice from the police. Instead the Met Police advise:
Make sure your jewellery is not visible.
Plan your journey in advance.
Avoid dark or deserted areas late at night.
Be aware of your surroundings and stay alert to what’s going on around you.
http://content.met.police.uk/Article/Kee...0010410680
Personally I would recommend that people think carefully before using some of the alleyways around Forest Hill late at night, but I believe the main roads, residential roads, and public transport are generally quite safe.