A sex education policy which appeared on an academy trust's website has been criticised as "explicitly homophobic".
A bisexual teacher, who saw the policy on the East Midlands Academy Trust's website when considering applying for a job, said it was from the "Dark Ages".
The Trust said the section, which said it "will not permit the promotion of homosexuality or bisexuality," was old.
It was removed from its website after it was queried by the Local Democracy Reporting Service.
Section 11 of the trust's relationships and sex education policy, headed "homosexuality", said the trust recognised the "need to provide education related to the spread of HIV/AIDS which will, of necessity, include reference to homosexuals and bisexuals".
At 11.2 it added that "the trust will not permit the promotion of homosexuality or bisexuality."
The teacher, who did not want to be named, said it was a throwback to Section 28 legislation, which banned schools in the late 1980s through to the early 2000s from "promoting" homosexuality.
It was widely condemned and repealed in 2003. In 2009, then Prime Minister David Cameron apologised for the policy.
To use similar language now was "at worst deliberate, and at best deeply ignorant", said the teacher, who described it as like something from the "Dark Ages".
"It is explicitly homophobic and it is difficult to read it any other way. I was considering applying for a job until I saw the policy which made it clear that this was not a school for me. I just feel like Section 28 is not dead. It is alive and well in Northamptonshire."
The trust, which runs Prince William School in Oundle and the Northampton International Academy, said the "old" policy had been developed "under the existing Department for Education guidance from 2000". It said the policy had been reviewed and a new version would be presented to its board in April.
"As a trust, we strongly believe in equality of opportunity for every pupil and teacher across our schools," a spokesman said.
"The relationships and sex education delivered within our schools is fully inclusive."
A Department for Education spokesman said all secondary schools must have regard to the new Relationships Education, Relationships and Sex Education and Health Education statutory guidance from September.