Consequent and Consequential
From 'Vocabulary' part of The ABC Of Plain Words by Sir E Gowers (1951)

Consequential has now only two meanings in common use. It retains that of self-important, and in legal language it signifies a secondary and incidental result, especially in the phrases consequential damages and consequential amendments. These latter are formal amendments made necessary by the carrying of some other amendment. For all other purposes consequent is the adjective of consequence. Thus a Minister might say "This amendment is consequent on a promise I gave on second reading" and "This amendment is consequential on one accepted yesterday".