The Scottish devolution referendum of 1979 reaches its threshold and a Scottish Assembly is created eighteen years early, elected by First Past the Post. When the Tories lose power in the UK in 1991, Labour enters office, but its one-term Government is perceived to be a failure, allowing for the SNP to enter office in a coalition with the Liberals in the 1995 Scottish election. A referendum on independence is narrowly won by the Scots in 2002, following the re-election of Michael Portillo's Conservative government.
Meanwhile, in their 91-96 term in office, Labour introduced devolved assemblies for Wales and the English regions, and these proved to be strong bedrocks of Labour power in the country, elected by STV every three years. By 2013, the North East regional assembly has never passed out of Labour majority control, and Wales and the North West have only been held briefly by Conservative-led coalitions. With the West and East Midlands being the only regional assemblies likely to swing in either direction, serious consideration is being given by the unpopular Conservative UK government to the abolition of the system, which is strongly opposed by Labour.
In 2007, following the death of Princess Diana and a record rise in unpopularity for the monarchy, Scotland under a Lab/SDP coalition holds another referendum on whether to become a republic, which is won by the narrowest of margins.
This sounds like a terribly interesting TL, I have to say. Here are the Governments I had in mind.
UK Government
1979-1991: Margaret Thatcher (Conservative)
1991-1996: Roy Hattersley (Labour)
1996-2003: Michael Portillo (Conservative)
2003-present: ? (Conservative)
Scottish Government
1981-1986: Conservative/Liberal coalition (Devolved)
1986-1995: Labour majority (Devolved)
1995-1999: SNP/Liberal coalition (Devolved)
1999-2003: SNP majority (Devolved)
2003-2006: SNP majority (Independent)
2006-present: Labour/SDP coalition (Independent)
Welsh Government
1996-1999: Conservative/SDP coalition
1999-2008: Labour/Liberal coalition
2008-2011: Labour majority
2011-present: Labour/Plaid coalition
North East Government
1996-present: Labour majority
North West Government
1996-1999: Conservative/Liberal coalition
1999-2002: Labour/SDP coalition
2002-present: Labour majority
West Midlands Government
1996-2005: Conservative majority
2005-present: Labour majority
East Midlands Government
1996-2002: Conservative majority
2002-2005: Conservative/Liberal/SDP coalition
2005-2008: Labour majority
2008-present: Labour/Liberal coalition
South East Government
1996-2005: Conservative majority
2005-2008: Labour/Liberal/SDP coalition
2008-present: Conservative majority
South West Government
1996-1999: Conservative majority
1999-2002: Liberal/Labour coalition
2002-2005: Conservative majority
2005-2008: Liberal majority
2008-present: Conservative/Labour coalition