4. He Knows How To Spot A Fake
Of course, what starts as an innocent look around the Louvre quickly becomes something much bigger. And what might have swayed the Brig/Kate and their selection panel for the curatorial post is just how quickly he solves the mystery of the multiple Mona Lisas and the secret their owner's hiding. Not that Count Scarlioni, or Scaroth of the Jagaroth as he's more properly known, is very good at covering it up. At least six copies of the prized artwork are on sale to the highest bidder to fund the Count's experiments in time travel. That's one true painting & five fakes drawn from a massive cache of them. And all it takes for the Doctor to start making things right is a quick hop back to Renaissance Italy and a felt tip pen. Such cheap security measures could only be executed by a man with infinite reserves of culture & cunning, and this guy has both. Plus it negates the need to take on a security guard and drain UNIT's funds in the process of paying him. Which would no doubt have crossed the Brig's mind as he sat down to review all the applications even if he did think this incarnation was barmier than the first two put together.