The agency, formerly known as Top Banana Team, now employs 34 people, compared to the team of 22 it had when it moved to new offices at the start of 2010.
TBT managing director Pete Saunders said the agency was taking on two office units next to its existing premises.
"The additional units will allow room for up to 65 people in the longer term," he said.
Joe Goss and Diane Shearn have joined as process and analytics managers. Their remit will be to support TBT’s work with two major IT clients.
Goss was formerly based in Amsterdam as a supply chain manager at Cisco Systems.
Shearn joins from Datasharp Integrated Communications, where she was office systems manager.
TBT director Ed-Craven Smith said: "We are delighted with the way that TBT is developing in 2011 and offering more complex and analytical services for our key clients."