There are potential challenges with making part of a role redundant (which contractually maybe what this is) HMRC tend to look very closely at any tax free payments if the person remains employed in other "roles". There are risks involved.

But continuous service starts from beginning not from a date a role was added IMO.

Andrea
There is only redundancy, and redundanncy payments, if there is a dismissal - do you intend to completely end the employment contract of this person? If not, what will happen to them?

Continuous service should be the date they were first employed with the employer.

You could hold redundancy consultation with them based on a % of their role being made redundant... it could be a case of them accepting continued employment on less hours or having their employment ended on grounds of redundancy and receiving a payment. They would not receive redundancy pay if the remain employed.

Always a tricky one, could be a worth a call to Acas in the first instance.