Upton, who will be succeeded in her South Central BDM role by Tracey White from July, will report to senior adviser Matthew Wyles.
Sean Oldfield, chief executive of Castle Trust, said “Castle Trust is on a path of rapid growth - it is this growth which enables us to promote talented people rapidly into senior roles.
“In the short time that Alex has represented our company in the South Central region, she has earned the respect of her colleagues across the business and built an excellent reputation amongst our intermediary partners.”
Upton added: “Castle Trust is a remarkable business and fabulous place to work. I’m proud to have been given such an important role in the development of the business.
“We have a great team of BDMs and I’m looking forward to working with them to deliver our objectives.”