The agency – which is headquartered in San Diego and specialises in online registration and event management software – has axed its director of EMEA David Preston this month.
Active Network strategy director Anthony Miller told C&IT: "We have got some very exciting changes, but David has moved on. With the technology industry, everything moves so fast."
He added the business, which is based in London’s Westbourne Grove and has around 25 employees, was "growing very quickly".
Latest annual accounts filed at Companies House for Active Network (EU) show the business had turnover of more than £1m in 2008, up from £134,884 in 2007.
Its profits were £43,398 in 2008, up from just over £8,000 the previous year.
Former Active Network director EMEA David Preston said he was now "actively looking at options" and would consider moving to another agency, or in-house.
Preston had worked at the agency since April 2008 after a two-year stint as managing director of DMS, part of the Grass Roots Group.
He also worked as event programme manager for IBM for three years from 1998 to 2001.
"They had been talking about changes to the organisational structure for some time," added Preston.