Castle, from Bloxwich, Walsall, recently completed her politics and international relations degree at the University of Reading, during which time she undertook voluntary work with British Red Cross and the West Midlands probation service as well as part-time retail jobs.
The move will ensure the company continues to meet its 24 hour decision and quotation service, which is currently receiving record applications.
Crystal Mortgages is enjoying its best year to date with £201m received in new business applications between January to September, with completions up substantially across all three quarters.
Roger Dewsbery, senior underwriter at Crystal Mortgages, said: “We are having to employ new members of staff to cope with demand, and Emma has the skills and enthusiasm to become a valuable member of this customer facing team, on which so much depends.”