Section 28 was a controversial amendment to the United Kingdom's Local Government Act 1986, enacted by the Local Government Act 1988 on 24 May 1988 and repealed on 18 November 2003. 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"<1>.
Some people believed that Section 28 prohibited local councils from distributing any material, whether plays, leaflets, books, etc, that portrayed gay relationships as anything other than abnormal. Teachers and educational staff in some cases were afraid of discussing gay issues with students for fear of losing state funding (see Controversy over applicability for more information).
No successful 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, transgender, and bisexual student support groups in schools and colleges across Britain were closed due to fears by council legal staff that they could breach the Act.<2>
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Despite successive defeats in the House of Lords of attempts to repeal Section 28 in England and Wales, the Labour government passed legislation to repeal this section as part of the Local Government Act 2003. This passed the Lords and received Royal Assent on the 18 September 2003 and the repeal became effective on the 18 November 2003.
http://en.wikipedia.org/wiki/Section_28Thatcher proved that the bigots don't want a proper definition of "promotion of homosexuality" - if it's unsure, teachers and schools won't take the risk, and it will end up stopping more discussion of homosexuality than something precise.