(3)in determining whether a trade mark is adapted to distinguish as aforesaid, the tribunal may have regard to the extent to which (a) the trade mark is inherently so adapted to distinguish, and (b) by reason of the use of the trade mark or of any other circumstances, the trade mark is in fact so adapted to distinguish : Provided that in the case of a trade mark which has been continuously used (either by the applicant for the registration or by some predecessor in his business, and either in its original form or with additions or alterations not substantially affecting its identity) in relation to which registration is applied for, during a period from a date prior to the 25th day of February, 1937, to the date of application for registration, the Registrar shall not refuse registration by reason only of the fact that the trade mark is not adapted to distinguish as aforesaid, and may accept evidence of acquired distinctiveness as entitling the trade mark to registration.