For the purposes of this section, and of any regulations under this Act relating to the Appeal Board, the expression ‘employer’ shall be deemed to include any local authority which on the twelfth day of October, nineteen hundred and forty-six, was a promoter of any tramway, and the expressions ‘employees of the tramways’ and ‘tramway employees’ shall be deemed to include every person who is employed in connection with the public transport undertaking of any such local authority.”