Perverting the Course of Justice
Offence: Indictable, Common Law
Relevant sentencing case law
concealing evidence - 4 months to 18 months, possibly longer if serious crime
R v Francis-McGann  1 Cr. App. R. (S.) 14.
Speed camera case. Appellant was an army captain. He phoned the police to say that the vehicle had been exported, and subsequently sent a letter to the police. Convicted after trial. Sentence of three months imprisonment upheld.
No pressure on Kier Starmer, mind you ...