78. If in any legal proceeding in which the validity of the registration of a trade mark comes into question, a decision is given in favour of the proprietor of the trade mark, the tribunal may grant a certificate to that effect, and if such a certificate is granted, then in any subsequent legal proceeding in which the said validity comes into question, the said proprietor on obtaining a final order or judgment in his favour shall, unless the said final order or judgment for sufficient reason directs otherwise, be entitled to his full costs, charges and expenses as between legal practitioner and client.