Property vested in any person on any trust or by way of mortgage shall not, in case of that person becoming a convict within the meaning of the [33 & 34 Vict. c. 23.] Forfeiture Act, 1870, vest in any such administrator as may be appointed under that Act, but shall remain in the trustee or mortgagee, or pass to his co-trustee in right of survivorship or devolve on his personal representative as if he had not become a convict:

Provided that this enactment shall not affect the title to the property so far as relates to any beneficial interest therein of any such trustee or mortgagee.