Complex sentence: The high proportion of students living in the constituency could have contributed to the victory of the Lib Dems here as at the 2005 election the Liberal Democrats opposed the Labour government's Higher Education Act which was also opposed by a large number of students.
Split into simpler sentences: The high proportion of students living in the constituency could have contributed to the victory of the Lib Dems. This is because (as was the case at the 2005 election) the Liberal Democrats opposed the Labour Government's Higher Education Act that was also disagreed with by a large number of students.