The only problem is that there is a detailed official statement that explicitly identifies Johnson as having been in Perugia that weekend (in addition to Blair), and at least two sources at the airport who agree that Johnson was there recently. The later unofficial clarification from the pres. of the airport, in contrast, is not very compelling. We're seeing now what happens when a leader and his subordinates gain a global reputation for lying—people can't take them at their word, even on those occasions when they might actually be telling the truth. The PMs visit to a Russian oligarch, at a particularly fraught time, would absolutely be the kind of thing a liar might deem to be worth lying about. The mystery will be solved once the passengers on the flights in question are identified, and locatable photos of Johnson that Saturday and Sunday eventually emerge.