“Ms Parker Aranha [the representative of the Secretary of State] did not accept that the claimant satisfies these conditions, all of which must be met for entitlement to higher rate mobility component on this special basis. She referred to the Commissioner’s decision in R (DLA) 7/02 which stated in paragraph 15 that 12(6)(c) is “only satisfied if the constant presence of an adult is necessary in order to intervene and deal with the claimant if and when he actually starts to become disruptive”