Section 3. The said land, under such lease agreement between The Bell Telephone Company of Pennsylvania and the Borough of New Hope as shall be mutually acceptable to the parties, shall be further subject to the unrestricted right to use by the borough for any municipal purposes for a period of five years from date of the conveyance provided for herein, and thereafter until such time as the telephone company requires the property, or any portion or portions thereof, for its own business purposes: Provided, however, That the borough shall be responsible for all taxes on the entirety of said property for the said five year period, and thereafter for all or such portion of the taxes as the area of the borough's continued use of the property bears to the area of the entire property.