Toone laid on both goals as United scored twice in four minutes early in the second-half. But the comfortable manner that the Red Devils saw the game out rather betrayed a first-half in which the home side put up some stiff resistance. And City could have even gone ahead if it wasn't for a fine save from Mary Earps just before the break.
It was a tale of two goalkeepers in the first period with City's Olivia Clark making several fine interventions to keep United at bay. At the other end, World Cup Golden Glove winner Earps was a virtual bystander until called upon to make a smart save low to her left.
The Robins' resilience was broken in the cruelest way possible five minutes in to the second period. No player in the WSL had taken more shots without scoring this season than Hinata Miyaza, but she kept shooting and got the fortune that sometimes comes with persistence when her strike took a heavy deflection to leave Clark completely stranded.
United were quick to double their advantage when Toone found Nikita Parris to head home and saw the game out uneventfully as a young Bristol City side were unable to create the goal that the record Ashton Gate crowd craved.