Bedfordshire Police issued the following statement yesterday:
This is good communication from the police. Although the alert doesn’t say when the buzzard was found it sounds as though it was a recent discovery and IF it does turn out to have been poisoned, the toxicology results may not be available for several weeks so this early police alert provides local dog walkers etc with due warning.
Good work, Bedfordshire Police.
Raptor Persecution UK 
We had a similar siuation a couple of years ago. Two dead Buzzards in a horse paddock about two kilometers from our house. Post mortem and toxicology analyses revealed that one Buzzard contained a half digested rat and that both carried high doses of an anti-coagulant. Presumably, rat poison was put down somewhere; a rat ate some; either the rat died and was scavenged or the birds caught a weakened rat. The conclusion was that this was a (very) unfortunate accident. No suggestion that the rat had been laid deliberately – no game-rearing anywhere near although they were on farmland. Whatever, it was a salutary lesson on the careful use of rat poison. Dispose of any dead rat or mouse securely. Not to land-fill (unless you hate gulls). Advice given to Linda and me was to incinerate the corpse.
Hope everybody knows that rat poison is now in the human food chain due to overuse! And I don’t mean warfarin.
I hope that the police announcement is a sign that they are getting the message about the need for public warnings that lethal poisons are about.
The use of a poison goes beyond illegal raptor killing.