The power that enables the Parish Council to contribute to the costs of mowing the Church Grounds is given by:
Local Government Act 1972
Section 214: Cemeteries and Crematoria.
1) The following authorities, that is to say, the councils of districts, London boroughs, parishes and communities, the Common Council and the parish meetings of parishes having no parish council, whether separate or common, shall be burial authorities for the purposes of, and have the functions given to them by, the following provisions of this section and Schedule 26 to this Act
6) A burial authority may contribute towards any expenses incurred by any other person in providing or maintaining a cemetery in which the inhabitants of the authority’s area may be buried.