Section 13 Registration in Part A to be conclusive as to validity after seven years.

In all legal proceedings relating to a trade mark registered in Part A of the register (including applications under section thirty-two of this Act) the original registration in Part A of the register of the trade mark shall, after the expiration of seven years from the date of that registration, be taken to be valid in all respects, unless—

Nothing in subsection (1) of section five of this Act shall be construed as making applicable to a trade mark, as being a trade mark registered in Part B of the register, the foregoing provisions of this section relating to a trade mark registered in Part A of the register.