Very well. On what charge does he summon the constable?
I suspect this is a tongue-in-cheek post but what the heck.
The duties of the police, then as now, were the protection of life and property, the maintenance of order, the prevention and detection of crime and the prosecution of offenders against the peace. The assault on Stride, if an injury was sustained, would have been an assault occasioning actual bodily harm under s.49 of the Offences Against the Person Act 1861. The assault itself and the production of a knife by pipeman were certainly more than enough to constitute a Breach of the Peace.
In addition to Stride, I could see Coles or Mackenzie as being interrupted. It's not easy to have the privacy to rip-em-to-bits in a very crowded East end with coppers afoot.
Actually, it seems only the coppers were afoot in Castle Alley. The policeman interviewed for the inquest all said no one really used the Alley, which was parked full of vans, wagons and barrows, and that not all of them were checked to see if someone was sleeping in them. One of the coppers had even had his private picnic at the same lamppost where Alice was killed.
Castle Alley was apparently quiet and eerily reminiscent of the murder of Polly Nichols. No one about, the police saw and heard nothing, a freshly killed woman and still he got away.