English: This chart effectually summarises an unusual transition in UK elections: In 2001 to 2005 there were 72 Scottish constituencies who elected MPs to sit in Westminster. These are represented in the first bar. The Speaker is shown in each bar as a white block striped with red, this is Michael Martin

As a condition of the union between England and Scotland, Scotland was traditionally overrepresented in the Westminster Parliament, compared to England. Following the creation of the Scottish Parliament in 1999 it was decided to redraw constituency boundaries so that the average population of Scottish constituencies was nearer the English average once the new Parliament in Edinburgh had settled down, thus reducing the number of constituencies from 72 to 59. The Boundary Commission re-drew each constituency in time for the 2005 General Election. People worked out from ward-by-ward election data what the new (i.e. yet-to-be-formed) constituencies would have elected on a plurality of the votes in 2001. The middle bar represents this data.

The final bar represents the actual results of the 2005 election. Thus the middle bar with the bar on the right and not the bar on the left with the bar on the right may provide a better model of swing in Scotland from 2001 to 2005.