The police can ask witnesses and victims what happened without a legal representative present. That's exactly how Mr Philpotts should have been treated by the way, as a witness and a victim, not a suspect. But hey, I guess at least that officer is one closer to his monthly arrest target, so the police must be doing their job well.
Being arrested might grant you certain extra legal rights, but it also deprives you of a fairly important one - your liberty. Please stop trying to argue that being arrested was to Mr Philpott's advantage, that's completely nonsense and you know it.