Re: downvote here
"The problem as far as the cops are concerned (not anyone interested in individual rights and justice) is that it is very hard to get a conviction from a jury when trying someone for conspiracy."
However the police do find it useful to do a "fishing expedition" by arresting someone "on suspicion of conspiracy to...". They hope the search that the arrest enables will find some evidence of real crime. This can happen if you have a social connection to a suspect in an investigation that is going nowhere. If they find nothing then they don't proceed to a charge for the purported conspiracy.
Any proven conspiracy offence used to be regarded extremely seriously by the courts - irrespective of what the conspiracy was supposed to be about. IIRC before the Blair government made everything an "arrestable" offence - the "suspicion of conspiracy to..." was a safe way to make an arrest of apparently innocent people.