Lancaster was a constituency of the House of Commons of the Parliament of England then of the Parliament of Great Britain from 1707 to 1800 and of the Parliament of the United Kingdom from 1801 to 1867, centred on the historic city of Lancaster in north-west England. It was represented by two Members of Parliament until the constituency was disenfranchised for corruption in 1867.

The Representation of the People Act 1867, known as the Reform Act 1867 or the Second Reform Act, is an act of the British Parliament that enfranchised part of the urban male working class in England and Wales for the first time. It took effect in stages over the next two years, culminating in full commencement on 1 January 1869.