This incident highlights the reason people should be allowed to carry weapons with which to defend themselves. The victim was outnumbered, an often seen trait of such attacks, and was left unassisted by police officers who cannot possibly respond to crimes as they occur. The victims of such crimes are thus left to fight bare handed, at the mercy of violent attackers who arm themselves regardless of the law.
In many cases handing over your belongings will not stop an attacker or group of attackers from seriously harming you. In such situations you are left to attempt to defend yourself, unarmed.
Surrey Police are appealing for witnesses - which, unfortunately is all the police practically can do after such incidents occur.
Even a CS gas pistol, sold over the counter in France would have offered a chance for the victim to escape. Unfortunately these are not allowed to be owned in the UK.
CS gas pistol - test video