Where the rules of a pension scheme confer a power, as a matter of domestic law, upon the amendment of its Trust deed, to reduce retrospectively the value of both men’s and women’s accrued pension rights for a period between the date of a written announcement of intended changes to the scheme and the date when the Trust deed is actually amended, does Article 157 of the Treaty on the Functioning of the European Union (previously and at the material time Article 119 of the Treaty of Rome) require both men’s and women’s accrued pension rights to be treated as indefeasible during that period, in the sense that their pension rights are protected from retrospective reduction by the use of the domestic law power?