Section 12A. If on appeal to the appeals court or the supreme judicial court pursuant to section twelve the claimant prevails, the court shall allow the claimant, in addition to the award in the judgement, an amount equal to the reasonable cost of his attorney's fees, briefs and other necessary expenses that result from the appeal. When any party in interest obtains an enforcement order from the superior court department of the trial court pursuant to said section twelve, the court shall also allow the party the reasonable cost of attorney's fees, briefs and other expenses provided for by this section.