Possible Clues:

• There was something about that chap Albert
• One acting for monarch who is a minor
• King's sub
• Fellow pushed back after monarch's return?
• Person appointed as acting monarch
• Ruler standing in for monarch
• Sovereign's sub
• Here's a stand-in about the chap
• Ruler has say when in charge
• Soak outside toilet on plane, say, finding way through central London