This case involved a prison officer who was in the 'Classic Section' of the Principal Civil Service Pension Scheme (PCSPS) i.e. she had been in long enough to avail of particular benefits and before changes were made for new entrants, such as the right to retire at 55 (in her case in 2019) without a reduction in her pension provided that she was then still in service, and the right to double-count each year of service for pension purposes after her first 20 years of service. 

When GS4 took over the service it was TUPE protected, or equivalent, but she lost out on the important pension protection of the right to take unreduced pension from 55 instead of 60, because her removal from the civil service and transfer to GS4 meant she was deemed to have "resigned" from the CS pension scheme.

Ms Ellis had taken her case to the Pensions Ombudsman (where she lost) and the High Court (where she won). The Court of Appeal has upheld the appeal of the Cabinet Office against the High Court decision for a number of reasons, "First and foremost, the term "resignation" is defined in rule 1.13 [of the PCSPS] as meaning "termination of service or voluntary retirement from the Civil Service before pension age". Had the words "termination of service" been intended to be limited to voluntary termination, it would have been easy to move the word "voluntary" to qualify both "termination of service" and "retirement from the Civil Service before pension age"."

So, on this construction, according to the Court of Appeal, presumably all civil servants transferred to the private sector will be deemed to have resigned from the civil service pension scheme and will lose out on benefits applicable only to those who remain in the civil service at the time of retirement. Civil servants and their representatives may wish to read the detail of this case and seek legal advice:
http://bit.ly/1Bq7oUC