Eric Partridge, in his Useage and Abusage
writes, 'As to cliches, I daresay we are all in agreement.
According to Eric Partridge - Usage and Abusage
, a guide to good English - these groups and others should be referred to in the singular when treating them as a single entity ( ie, Merseyside Police is recruiting more officers) and become plural when referring to them as a group of individuals ( ie, Police are hunting a knifeman).
Eric Partridge, in Usage and Abusage
, defines a cliche as "an outworn commonplace; a phrase (or virtual phrase) that has become so hackneyed that scrupulous speakers and writers shrink from it because they feel that its use i an insult to the intelligence of their auditor or audience, reader or public".