LOL, I hadn't heard that one before, probably the same as "trust me" or "honestly"... (although it might be also be true to say that distrusting someone who uses "fact" would indicate more about the reader than the writer?)
Anyway, back to the topic:
Honestly, you gotta trust me on this - Home Office have no powers to instruct Police on Operational matters. fact.
And if you don't trust me, just look it up for yourselves:
Google "Home Office power over police UK", or "Does the government control the police UK".
Answers will clearly show that police operations are independent of government and that the home office has no power over police operations...