Is it sufficient to make an alteration material if in the words of Halsbury's words it "varies the legal position of the parties as ascertained by the deed in its original state"?

In short, then, it is sufficient to make an alteration material if in Halsbury's words it "varies ... the legal position of the parties as ascertained by the deed in its original state, or otherwise varies the legal effect of the instrument as originally expressed". All that is required to constitute a material alteration is a change in the "legal incidents" of the instrument (per Greer L.J. in Koch v. Dicks, at p. 324). It need not alter the obligations under the instrument itself. In fact, it is sufficient that the alteration would alter the "business effect" of the instrument (per Brett L.J. in Suffell v. Bank of England, supra).