I wonder if John Buck ever watched the TV back in his days as ambassador in Portugal in 2007? Or read the news? I wonder if perhaps he took it upon himself to get personally involved in an international news even out of concern and a desire to help personally? Or perhaps because he fancied Kate McCann? No it must be more sinister than that, involving conspiracy and cover up.
While he may have had various personal or professional reasons to head to the Algarve, I can think of a few potential reasons concerning his presence.
For what it's worth, a former (witty) British ambassador to somewhere in the Middle East (?) whose name escapes me wrote various accounts of his experiences. One - which caught my eye at the time - concerned an internationally newsworthy but chaotic situation in a country that didn't have the resources or the experience to deal with vast quantities of British journos and TV crews. Although not strictly within his mandate, he facilitated organising TV satellites, etc., to help make the onslaught of his country's press more manageable, thus reducing the risk of a diplomatic rift on that front. While Portugal wouldn't have needed help organising TV satellites, the PJ didn't have an official press liaison spokesperson and were - officially at least - bound by so-called judicial secrecy.
A potentially more thorny issue may well have arisen if he'd been made aware of the fact that the same PJ team had been in charge of the Cipriano saga. Another slippery stair incident would have been unlikely to bode well for diplomatic relations.