so when the police turn up and find a stabbed dead man they're supposed to make an on the spot judgement call that you're "clearly innocent" ,take the dead body away and just let you get on with with your business ? the law doesn't really work that way in the UK. also if you've been formally arrested you're entitled to a duty(free) solicitor, unless you want to hire your own.
Yeah I'm not up on the UK rules. Here, in similar circumstances, if there is no Probable Cause to believe a crime was committed by the Homeowner, the homeowner and any witnesses would be brought down to the station and interviewed. If there is no surprises they would be brought back home and the investigation would run its course. If at some point, information or evidence comes to light that all wasn't as it seemed and the homeowner is now a suspect the police would present the evidence to a judge who would then determine of probable cause exists to issue a warrant. At that point you would be advised of your rights and if you can't afford an attorney, and you have to show you can't then a pretty lousy public defender would be assigned to your case.