Perry, the fifth seed who had lost her previous fourteen meetings with the three-time British Open Champion, played the game of her life to win 6-11 12-14 15-13 11-5 11-9 in 76 minutes.
"I can't believe I just beat the World No.1," said an ecstatic Perry, from Banbridge, near Belfast, afterwards. "I normally struggle to get a game off Nicol."
The win came from a stunning cross court nick shot after David served to try and save her third match-ball.
"That's definitely my best ever win," added Perry, the 32-year-old World No.8. "I've changed my game since I last played her - and did a lot of work on my movement over the summer."
But, otherwise, the day belonged to the hosts - with two English players through to the women's semi-finals for the first time since 2002.
Third seed Alison Waters and fourth seed Jenny Duncalf will provide the domestic interest in the women's semi-finals.
Duncalf went one step closer to reaching the final for the second year in a row after beating eighth seed Vanessa Atkinson, the former World Champion from the Netherlands, 11-1 10-12 11-6 11-4.
"You can never underestimate Vanessa - after all, she has been a World Champion and World No.1," said the 26-year-old World No.6. "She's got great racket skills.
"I felt I played well today and am improving all the time. This week I'll be trying to close the gap the gap behind Nicol David, the World No.1."
Duncalf will face three-time champion Rachael Grinham, the second seed from Australia who recovered from a game down to beat Lancashire's Laura Massaro 5-11 14-12 11-7 11-7.
Alison Waters claimed her first appearance in a British Open semi-final after beating Australian qualifier Donna Urquhart 6-11 11-5 11-3 11-7. The former British National champion will now meet Madeline Perry for a place in the final.
National Squash Centre, Manchester
Women’s Championship Quarter-Finals:
[5] Madeline Perry (IRL) bt [1] Nicol David (MAS) 6-11, 12-14, 15-13, 11-5, 11-9 (76m)
[3] Alison Waters (ENG) bt [Q] Donna Urquhart (AUS) 6-11, 11-5, 11-3, 11-7 (31m)
[4] Jenny Duncalf (ENG) bt [8] Vanessa Atkinson (NED) 11-1, 10-12, 11-6, 11-4 (39m)
[2] Rachael Grinham (AUS) bt [6] Laura Massaro (ENG) 5-11, 14-12, 11-7, 11-7 (54m)
Women's Championship Semi-Finals Line-up:
[5] Madeline Perry (IRL) v [3] Alison Waters (ENG)
[2] Rachael Grinham (AUS) v [4] Jenny Duncalf (ENG)
For further information, visit the internationalSPORTgroup British Open – Manchester 2009 Official Website,, email: or contact Press & Media Manager Peter Schmidl on mobile +49 172 7211162, Skype: peter.schmidl1 or email
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Defending champion Nicol David, the Malaysian super star who this month began her fourth successive year as World No.1, crashed out of the women's championship of the internationalSPORTgroup British OpenManchester 2009 after squandering three match balls in the third game to Ireland's Madeline Perry.