Who is left dismayed

"The European commission president, Jean-Claude Juncker, had privately urged May to hold a general election on several occasions, hoping she would be able to secure a big enough majority to free herself from the whim of the hardline Brexiters in the cabinet, only to be left dismayed by the result." (The Guardian.)

Who is said (in the above) to be left dismayed: Jean-Claude Juncker or the PM May?