No, er, ah, Doug. It's not. Even if the malfeasance was British rather than American, it would not come down to MI5 but MI6. (But then I suppose you still regard talk of a US recession as "horse-pucky.")

Here's a link from The (London) Times today, which gives the background to McGoH's point above: Claims of a Lockerbie cover-up

Two governments and many gullible victim relatives (mostly on the US side of the water) will now rest content that Megrahi's conviction sovled the crime. For those who believe the atrocity was in response to Americans killing a similar number of Iranians a few months earlier (as the US admin itself maintained for a long time afterwards) many questions remain unanswered. Likewise for those who believe Megrahi could not have done the job on his own (as Megrahi's prosecutors also believed).

Someone contributing a comment in the attached link recalled George Bush Snr's thoughtful response to the shooting down of that Iranian civilian aircraft, Flight 655: "I'll never apologise for the United States of America, ever. I don't care what the facts are." And that was before 9/11 gave US admins some excuse for their barbarities.