Monday’s news that Linklaters long-timer and U.S. head Tom Shropshire is to become drinks giant Diageo’s next general counsel came as a surprise to many for one standout reason: he was a senior partner hopeful bidding to take the reins from outgoing leader Charlie Jacobs.

Whether as senior partner or otherwise, he has long been touted as a future leader of the elite firm, with one partner at a rival firm saying he was “a great partner” and “strong on the firm’s U.S. strategy”. So naturally, given his eminence both within and outside Linklaters, people are asking—why make the move now?