(1) Subsection (2) applies where—
(a) the taxing officer of one House receives an application under section 3, and
(b) the bill of costs to which the application relates includes costs which relate to a private Bill but not to proceedings of that House.
(2) The taxing officer may—
(a) assess the costs himself, or
(b) ask the taxing officer of the other House or an authorised court officer to assess some or all of them.
(3) Subsection (5) applies where—
(a) an officer is asked under subsection (2)(b) to assess costs, or
(b) the Secretary of State asks the taxing officer of the House of Commons to assess costs relating to a Bill or to a provisional order.
(4) Subsection (5) also applies where an authorised court officer asks either taxing officer to assess costs—
(a) relating to a private Bill, and
(b) included in a bill of costs which the authorised officer is directed to assess by the court by which he is authorised.
(5) The officer concerned must—
(a) assess the costs, and
(b) give his opinion to the person who asked him to assess them.
(6) An authorised court officer may—
(a) for the purpose of assessing costs under this section, exercise any powers he has for the purpose of assessing costs under his authority, and
(b) receive fees for assessing costs under this section on the same basis as he would for assessing costs under his authority.
(7) “ Authorised court officer ” means an officer of a court who is authorised by that court to assess costs relating to its proceedings.