That means that Rhys Edwards' charges ended up with two wins in the tournament, good enough for fourth overall in the table that secured them a spot at next year's World Cup.
And while Tuson's late try was a bitter pill to swallow Snowsill found plenty of positives to take from the Championship.
"We were so close, it would have been a different story if we had got four wins," she said.
"But at the start of the season our aim for the Six Nations was to qualify for World Cup and we have done that.
"And we have done that from performing well and we can take that onwards, this is the start now with 18 months until the World Cup.
"I'm so proud of the girls for pulling together and putting in a really good performance against England.
"I really thought we could do it but it broke my heart when they got that try at the end.
"The forwards have been brilliant, every scrum and every lineout I'm confident they are going to win the ball and it gives us (the backs) the chance to run with it."