McNeil was educated at the co-educational, Roman Catholic Our Lady's High School, Cumbernauld before training as a graphic illustrator at Glasgow College of Building and Printing.

McNeill was a staunch opponent of the Iraq War[1] and campaigned for the right of protesters to picket the 2003 Scottish Labour Party Conference, which took place at the SECC in her own constituency.

On 2 July 2005, McNeill was a demonstrator in a Make Poverty History march in Edinburgh when the 31st G8 summit met at Gleneagles Hotel in Perthshire.

In 2007, McNeill narrowly retained the Glasgow Kelvin seat with a reduced majority in the wake of public opposition to the national Labour government's invasion of Iraq, a policy she opposed.

MacNeill was one of 5 Labour MSPs who was absent for a Scottish Parliament vote calling for the UK Government to reverse its decision to means-test the Winter Fuel Payment.

She has supported successful campaigns to grant Fair Trade status to the City of Glasgow and restore the Kelvingrove Park bandstand.

On crime, McNeill has sought better safety in Glasgow's city centre and the extension of community protections to its West End.

In 1999, at the Candlelight Chapel in Las Vegas, McNeill married Joseph Cahill, an advocate, a former police officer and Deputy Procurator Fiscal.