Police impersonation

Dressing up as a police officer in costume (e.g. for Halloween), or pretending to be a police officer for the purpose of play or a harmless prank toward an acquaintance is generally not considered a crime, provided that those involved recognize the imposter is not a real police officer, and the imposter is not trying to deceive those involved into thinking he/she is. Nevertheless, replica police uniforms sold in the UK must not be identical to the uniforms currently used by the police, and traders have been jailed in the past for selling on genuine uniforms

Question: can you dress as a cop for halloween
Answer: yes