“Entitlement 10.—(1) The entitlement of the person or persons by whom a claim for working tax credit has been made is dependent on him, or either or both of them, being engaged in qualifying remunerative work. (2) Regulations may for the purposes of this Part make provision- (a) as to what is, or is not, qualifying remunerative work, and (b) as to the circumstances in which a person is, or is not, engaged in it. (3) The circumstances prescribed under subsection (2)(b) may differ by reference to— (a) the age of the person or either of the persons, (b) whether the person, or either of the persons, is disabled, (c) whether the person, or either of the persons, is responsible for one or more children or qualifying young persons, or (d) any other factors. (4) …. Maximum rate 11.—(1) The maximum rate at which a person or persons may be entitled to working tax credit is to be determined in the prescribed manner. (2) The prescribed manner of determination must involve the inclusion of an element which is to be included in the case of all persons entitled to working tax credit. (3) The prescribed manner of determination must also involve the inclusion of an element in respect of the person, or either or both of the persons, engaged in qualifying remunerative work- (a) having a physical or mental disability which puts him at a disadvantage in getting a job, and (b) satisfying such other conditions as may be prescribed. (4) The element specified in subsection (2) is to be known as the basic element of working tax credit and the element specified in subsection (3) is to be known as the disability element of working tax credit. …” 24 The various regulation-making powers conferred by sections 10 and 11 have been exercised to make theWorking Tax Credit (Entitlement and Maximum Rate) Regulations 2002 ("the WTC Regulations"). Regulations 4(1) and 9 of, and Schedule 1 to, those Regulations are relevant to this appeal. To that extent, those provisions read as follows: “Entitlement to basic element of working tax credit: qualifying remunerative work 4.—(1) Subject to the qualification in paragraph (2), a person shall be treated as engaged in qualifying remunerative work if, and only if, he satisfies all of the following conditions (and in the case of the Second condition, one of the variations in that condition). First condition The person is employed or self-employed and— (a) is working at the date of the claim; or (b) … Second condition First variation: … Second variation: In the case of a joint claim where neither person is responsible for a child or qualifying young person, the person— (a) is aged at least 16 and undertakes work for not less than 16 hours per week and has a physical or mental disability which puts that person at a disadvantage in getting a job and satisfies regulation 9(1)(c); (b) is aged at least 25 and undertakes work for not less than 30 hours per week; or (c) is aged at least 60 and undertakes work for not less than 16 hours per week. Third variation: … Third condition … Fourth Condition …”