The mother of five didn't have everything go her way against favourite Ken Walker, of Dunedin, in the final. She won the first game 11-10 but fell apart in the second 3-10 before clawing her way back to win the best-of-three ends of tie break.
She only realised she had created history on Saturday in making the playoffs when she read it on the NZ PBA website.
Yesterday morning, before the semifinals, she received an inspirational text from fellow PBA player Tania Wheeler, of Wellington, whose campaign ended earlier this year.
"Great stuff, Tarsh. Do it for us girls," was the message from Wheeler.
It wasn't lost on Grimshaw who was remarkably calm going into the semifinal where she whipped Te Whao Gregory, of Waikato, 9-1, 10-6 while Walker showed Aucklander Steve Hoeft no mercy with a resounding 12-1, 9-1 victory.
"We're a minority in the PBA so I hope my winning today will make the women say, 'Oh jeez, it's possible to compete in the PBA and get that far'.
"PBA is excellent for bowlers because it makes them think a little bit more," she said, unsure why females seemed somewhat intimidated to enter that arena.
NZ PBA chairman Richard Corry said only 15 per cent of the field tended to be women.
Auckland's Linda Ralph, who was playing at the weekend, was the only previous woman to make it to a finals weekend but she failed to win a match in 2012.
Yesterday Grimshaw lost the first end of the tie break, won the second with the last bowl before fisting the air for the third one when Walker missed the kitty in trying to take it away to enforce her to play her last bowl.
Wily campaigner Walker pulled out every trick from his bag in the final.
Grimshaw lost her composure a little, battling a bout of jangled nerves that became more intense in the tie breaker.
Having secured the first game after they were locked 10-all in the last end, the player who finished fifth equal revealed she lost her bearings in the second game.
"He [Walker] like changed the length of the mat so I lost my weight and was falling short with my shots all the time."
Sensing a modicum of brittleness creeping into her game, he maintained the mat length to ask more questions.
Having won the toss, she gave away the mat to ensure she was going to have the last shot in the tie break.
Instead of retreating into a cocoon of resignation, the part-time Heinz Wattie employee drew on her mental fortitude consolidated over nine seasons of no-holds-barred bowls.
"When I don't do my best I just give myself a good talking to because that's when no one can hear me," she said with a laugh.
While mindful Walker was PBA No1 contender and winner of previous titles she didn't lose confidence in getting the job done.
"I didn't get here for nothing," said Grimshaw who has won a trip to Blackpool, England, and will now start raising funds with the help of her family and friends, although the PBA will subside her trip with a $1000 injection.
Grimshaw, who moved to Hastings more than three years ago for a change of scenery, sort of stumbled on to bowls when she joined a sports social club at the Kaipara Tavern in Helensville as a 26-year-old.
"The club used to be involved with darts and eight ball so one day it got into business house indoor bowls and I gave it a go and liked it."
The woman from nearby Parakai joined Helensville Bowling Club to become its second-youngest player.
"I learned bowls by playing against men and with them," she said, adding the late Ivan Kostanich was her mentor.
"He was in his 80s and a very good bowler who played in the Commonwealth Games," the Heretaunga club member said of Kostanich who won a PBA title in his 90s.
Wellington's Rob Ashton beat the Bay's Dean Drummond in the Scottish Open playoffs to secure the last position in next year's NZ team to play their Australian PBA counterparts at the East Cessnock club in NSW.
Ashton joins Craig Merrilees (Southland), Walker, Duane White (Dunedin) and this year's Transtasman Challenge individual winner Murray Glassey (HB) in the team.
Paul Sorenson, of Napier club, lost 9-4, 8-8 in the semifinals to Andy McLean (Dunedin) in the world indoor singles.
