Is There A Conflict of Interest When A Local Authority Acts As Deputy? 

Yes. There can be conflicts of interest when local councils get involved in the management of a person's financial matters.

This is particularly the case if a local authority is also making financial assessments to determine how much a person under their charge as deputy should pay the local authority to contribute towards the cost of their care package. The same conflicts can be applicable when the local councils act as a corporate appointee.