A simile for someone being over-qualified for a given task.  From Nicolson’s enchanting book about Sissinghurst.      

It was like having the engineer on the Aswan dam supervise the building of your pond.  Why was he doing it?

Source: Adam Nicolson, Sissinghurst: An unfinished history (London: Harper Press, 2009), p. 290

Photo credit: wallner at pixabay