[Thanks to James Medhurst of Employment Law Advocates for providing this case summary]
The EAT (Underhill P) has handed down its decision in Pothecary Witham Weld v Bullimore, which is authority for the proposition that the reverse burden of proof provisions in section 63A of the Sex Discrimination Act 1975 do apply to victimisation, unlike cognate provisions in section 54A of the Race Relations Act 1976, which have a different wording.
Section 63A of the 1975 Act was held not to be ultra vires because, although the Equal Treatment Directive does not require Member States to protect against victimisation, it is an important part of UK discrimination law and so the Secretary of State was entitled to maintain consistency by applying the Burden of Proof Directive to victimisation as well.
It was also observed that the cases of Chief Constable of West Yorkshire v Khan  IRLR 830 and Derbyshire v St. Helens Metropolitan Borough Council  IRLR 540 are cases of a very particular type, where the employer has taken action in order to protect his position in current litigation. In most cases, the complexities addressed in these cases simply do not arise and it will suffice for tribunals to follow the guidance in Nagarajan v London Regional Transport  IRLR 572.