Period to be taken into account by assessments revised on ground of unforeseen aggravation
62. On a review of any assessment under section 45(4) of the Administration Act the period to be taken into account by any revised assessment may include any period not exceeding three months before—
(a)where the review is in consequence of an application by the claimant, or a person acting on his behalf, the date of that application; or
(b)where the review is in consequence of a decision on a recrudescence question, within the meaning of regulation 43(3)(b), given under regulation 7(4) of the Prescribed Diseases Regulations, the date of the claim on which that decision was given,
if the medical board is satisfied that throughout that period there has been unforeseen aggravation of the results of the relevant injury since the making of the assessment under review.