John Major right?
The Tories in 1997 were destroyed by a perfect storm of hubris. They combined a long time in power which encourages self-interest, ideological division, un-charismatic leadership and voter fatigue. Add in an unexpected win in 1992 which prolonged their time in office artificially, the appearance of a viable alternative who had slicker PR and fresher faces to offer in Blair and New Labour and a few good potential candidates in strategically important seats opting out leaving Central Office with weaker B-tier candidates in their place.
The Dumfriesshire seat is a good example of everything coming into play at once. It was a heartland Border seat that should always vote Tory because it's a farming seat and is found too far away from Glasgow and Edinburgh to benefit from centralisation (#RIP Dumfries DVLA office, Dumfries HMRC office, Dumfries Royal Mail sorting office, National Museum of Costume, ability to staff the local hospital etc - all dead since devolution), where the popular incumbent (Sir Hector Munro) stood down and likely successor Councillor Marjorie McQueen, leader of "the women who washed" after the Lockerbie Air Disaster and absolutely would have been elected, chose not to run, forcing Central Office to rely on Plan B. Labour chose to target the seat hard (as in Blair visited in person the day before polling day) because of the relative size and significance of the county town Dumfries within the South of Scotland in-general. The loss of that seat made a wipe out in Scotland inevitable because that seat (and it's successor Dumfriesshire, Clydesdale and Tweedsdale) is the one the Tories CANNOT lose and have ANY hope for success. It would be like losing the Tories losing in North West Norfolk which has King's Lynn in it, it's just BAD - and yet they lost, to a charisma-vacuum shop steward with ZERO discernable talent except a willingness to vote the party-line who never achieved meaningful office named Russell Brown, who was gotten rid of after boundary changes for the current, Tory incumbent and future Secretary of State for Scotland David Mundell in 2005.
Your options for alt-history you can do around Major that I see are as follows:
1) Him not succeeding Mrs Thatcher in the first place
2) Him losing the 1992 election
3) Him losing the Maastricht vote in 1992 and getting booted by his own party and a part civil war as a result.
Major was NEVER going to win in 1997, so, depending on your choice here, we could have a very different Tory party and a very different set up which might cross into current politics. So which option do you choose?