the case thereafter described imposes a constructive trust on a person receiving by will property which the testator had intended to convey to another under an instrument which by mistake did not have that effect

1. the same result would have been effected through the court's reforming the instrument to include the inadvertently omitted property [a reformation effective against the testator's successor who was not a purchaser for value]

2. if reformation had been the theory of decision, it might have been noted that the deed was being reformed up -- ie to include more property than the original writing.

US cases have held 'reforming up' is improper as to land because of the Statute of frauds