I've not been following closely, but I believe that the reason the government lost previously when they tried to change the terms of civil servants redunancy pay, is because the existing provisions are set out in primary legislation (the Superannuation Act 1972).
I'm not an employment lawyer, but I believe that most employment contracts do provide for the terms of employment to be varied from time to time.
I'm not an employment lawyer, but I believe that most employment contracts do provide for the terms of employment to be varied from time to time.