Q 1. Yes , makes it potentially serious and merits urgent investigation and no further contact with worker in quesiton.

Was Brian told in advance that Simon would be coming back to provide his care? I know it was short notice, but even a phone call? Maybe this would have encouraged Brian to say more at an earlier stage?

Rob reported Brian's initial request to his manager...so was there any follow up with Brian to ask why he requested an alternative staff member? And whilst it was being investigated, was there absolutely no alternative to bringing in Simon to help Brian?

Rob should report Brian's latest comments to his manager and the Manager ought to refer the matter externally - to the local social work team

It clarifies the potential risk involved