But back stormed England as Tuson notched their third try of the match to ensure that while they had already relinquished their RBS 6 Nations title to Ireland, who completed the Grand Slam on Sunday, Gary Street's side ended on a winning note.
Amber Reed kicked England into an early 3-0 lead with a penalty and captain Sarah Hunter grabbed her fourth try of the competition, dotting down after 14 minutes.
Reed hit the post with the conversion however and back came Wales, who trimmed the gap to just three with a try from winger Charlie Murray on 20 minutes.
Lydia Thompson swiftly restored England's eight point advantage when she charged down Dyddgy Hywel's clearing kick and this time Reed was able to add the extras, handing England a 15-5 lead.
But Wales refused to lie down and Elinor Snowsill's penalty just before the break ensured the hosts went into the half-time interval within touching distance of last year's Grand Slam winners.
England required to add 30 to their advantage if they were to catch France in second place but it was Wales who added to the scoreboard first in the second half, Snowsill slotting her second penalty of the match after some concerted pressure from the hosts.
Wales could scent that England were there for the taking and they followed up that penalty with their second try of the match - York driving over from a lineout to touch down, handing the hosts the lead with ten minutes remaining.
But England hit back immediately, Tuson finishing off a fine move to put her side back ahead, 20-16 to the good, and the visitors held on to ensure they ended their campaign with a win.