The Secondary Heads Association established a foothold in FE with sixth-form college heads and vice-principals when their institutions were under local education authority control.
Last week SHA launched a big publicity drive saying it had 300 members in the FE sector. The high-profile campaign draws on support from prominent principal members, other than those in sixth-form colleges.
Michael Austin, principal of Accrington and Rossendale College, is quoted in the literature saying: "I decided to join SHA having looked at the alternatives, not only because of the excellent professional protection which they offer, but because of the extensive networking which goes on between members."
His words have angered others, particularly the activists in the Association of Principals of Colleges and the Association for College Management who claim a right to that ground. One leading APC member said: "If SHA is claiming 300 members then all I can say is they must have opened a college caretakers' branch."
The APC itself is looking to expand its power base, having twice suggested that the Association of Sixth Form Colleges merge with it to form a single voice for principals. There are also rumours that a merger is being mooted between APC and ACM, although this was denied by senior officials.
John Dunford, president of SHA, told The TES the membership of the two organisations was too narrow. "It is important to have an organisation that bridges school and college sectors. We are strong in both the 16 to 19 and 14 to 19 developments."
The spur, however, to the new recruitment drive was the birth of the Association of Colleges, formed from a merger of the Colleges' Employers' Forum and the Association for Colleges. "The new body is a college organisation and this will leave senior college staff vulnerable, exposed and in need of personal protection."
The SHA boasts a number of successful legal campaigns supporting heads under attack from their boards, including that of St Philip's Sixth Form College where the governing body was sacked following allegations of mismanagement.
But these claims have angered the APC and ACM further since they were taken to imply that legal services of similar calibre were not available from them.
It will also incense the CEF, since it claims to have the leading legal support service for principals and senior managers.
One leading CEF member said: "There is a combination of arrogance and ignorance in the stance that the association (SHA) is assuming."
Ben Bennett, president of the APC, said: "It's a free market and people will compete but our track record on dealing with people in trouble will keep us in the lead."