Wagtail
Super Star Member
- Joined
- Jan 15, 2013
- Messages
- 11,932
- Location
- St Helens, Tasmania, Australia
- Tractor
- JD 4105 / JD Z355E (48" deck)
Years ago a British teacher my father was doing a teacher exchange with got caught by that. He told a student he would come round come round in the morning & knock her up so she wouldn't be tardy. There were a few international calls made by the school sorting that one out.
A "knocker up" was an actual job so the expression is perfectly cromulent: Knocker-up - Wikipedia
As to 'knock it up', regarding manufacturing something, I believe that it goes back to carpentry when they would use nothing but wedging joinery and would have to hammer (knock) the pieces into place.