What is a "lasting improvement" and what is a lasting improvement?

Counsel then discussed the question of determining what was a lasting improvement. Counsel for the defendant urged that the time for deciding this question was the time at which proceedings were brought, 15th December 1975, and the proposition was not challenged. The subject of lasting improvements was also canvassed by D. C. McDonald J. in the Mildenberger case, and he accepted the view of Laskin J.A. (as he then was) in Gay v. Wierzbicki, supra, at p. 216, where he says that the term “lasting” refers to permanence, in the sense of “not being easily removable”.