The amendment stated that a local authority "shall not intentionally promote homosexuality or publish material with the intention of promoting homosexuality" or "promote the teaching in any maintained school of the acceptability of homosexuality as a pretended family relationship." Because it did not create a criminal offence, no prosecution was ever brought under this provision, but its existence caused many groups to close or limit their activities or self-censor. For example, a number of lesbian, gay and bisexual student support groups in schools and colleges across Britain were closed owing to fears by council legal staff that they could breach the Act.
There was also some question, after Section 28 passed, as to whether Shakespeare's homoerotic sonnets—nearly all of Shakespeare's sonnets—could be taught in the schools.
I was living in London—waiting tables, seeing plays, stealing silver, pining after British boys—when Section 28 was being debated. The law prompted Ian McKellen to come out of the closet and it prompted some righteous lesbian parents to tag Thatcher billboard with "Lesbians Mums Aren't Pretending." Coming at the height of the AIDS epidemic, Section 28 instilled panic. It felt like this law might the first of many anti-gay laws to come. Instead Section 28 was the beginning of the end for political homophobia in the UK. Because McKellen wasn't the only gay person to come out in protest. And you know what happens when gay people come out.
So thanks for that, Maggie.
UPDATE: Says Joe:
Section 28 was not repealed until 15 years later in November 2003. In 2009 Prime Minister David Cameron officially apologized for Section 28, saying that the Tories "had gotten it wrong." He added, "I hope you can forgive us."