Complex sentence: In the 1999,2002, and 2005 elections, the Labour Party published pamphlets publicising "Labour's Gay Lesbian and Transgender candidates", which is thought to be a world first by a mainstream national political party.
Split into simpler sentences: In the 1999,2002, and 2005 elections, the Labour Party published pamphlets advertising "Labour's Gay Lesbian and Transgender candidates". This is thought to be a world first by a mainstream national political party.