Section 55. The commissioner shall ascertain from the returns or otherwise the true market value of the shares of each corporation required to make a return under section twelve of chapter sixty-two C, and shall estimate therefrom the fair cash value of all the shares constituting its capital stock on January first preceding, which, unless by the charter of a corporation a different method of ascertaining such value is provided, shall, for the purposes of this chapter, be taken as the true value of its corporate franchise. From such value there shall be deducted the value as found by the commissioner of its works, structures, real estate, motor vehicles, trailers, machinery, poles, underground conduits, wires and pipes, subject to local taxation wherever situated.

For the purposes of this section the commissioner may take the value at which any works, structures, real estate, machinery, poles, underground conduits, wires and pipes are assessed at the place where they are located as the true value, but such local assessment shall not be conclusive of the true value thereof. For purposes of the deduction of the value of motor vehicles and trailers, the value of such motor vehicles and trailers as determined in accordance with the provisions of chapter sixty A shall be used.

The term ''real estate'', as used in this section and in section sixty-eight A, shall include the corporation's interest as lessee in such buildings on land held under a lease as by the terms of the lease are the property of and may be removed by the lessee, and such buildings, for the purposes of said sections shall not be deemed real estate of the lessor.