TimS,
Yes, AirForce 1 could also be a Gulfstream, or a C9, but on international trips is normally one of the (heavily modified) 2 747-200's.
Yes, the Japanese have 2 -400's (nearly always to be seen together). The Sultan of Brunei also has one (recently seen gracing the concrete at that famous Oxon airbase where everything seems to be happening at the moment!)
For the trip to Genoa today, what is Tony using?
1. A small 4 engined jet from Northolt?
2. A larger (and much more noisy!) 4 engined jet from the above-mentioned Base ("Beags" finest)?
3. A loaner from BA?
4. Or is he hitching a ride in AF1?
What he should be doing is taking G-BOAF for another test run, as a statement of confidence in the Conc!!