Scottish Tory leader Ruth Davidson and her team are said to have felt a mixture of relief and disappointment after the election results came in.

Strategists were happy to avoid a wipeout - the party held on to sole MP David Mundell - but the Conservatives again failed to make progress.

The harsh truth is that the 14.9% vote share was the worst result since the Scottish Tories were formed in 1965.

Inside the political bubble, Davidson fought a decent campaign.

She performed well in the leaders' debates, put forward a positive "blue collar conservatism" message and was even tipped for a move to the Commons.

In reality, Davidson failed to meet half of the four tests she set herself in the closing stages of the campaign.

The Glasgow MSP said she wanted the Tories to win more than one MP. This goal was not achieved.

She said the party should demonstrate an improvement in vote share. It fell.

Only the low-hanging targets were met, such as overtaking the Liberal Democrats and increasing the number of votes compared to 2010.

However, although Davidson inherited a divided party when she became leader in 2011, senior Tory sources believe she is blameless for the poor showing.

Part of her struggle can be traced to the tactic of pro-Union voters ignoring their gut preference by supporting the party best placed to defeat the Nationalists.

In practice, this meant the Scottish Tories losing votes to Labour and the Liberal Democrats, but getting little in return.

Davidson's party may have been the best option to challenge the SNP in various seats, but the reality of Scottish politics is that Labour and LibDem supporters were unlikely ever to back the Conservatives.

Senior party sources said a bigger obstacle to a Scottish Tory revival was David Cameron, who traded away progress north of the border for reaching out to voters in England by playing the anti-SNP card.

As Davidson sold the coalition message on welfare and the economy, Cameron talked up the SNP and complained that any Nationalist-Labour tie up would lack legitimacy.

The Prime Minister, according to party insiders, undermined another plank of Davidson's strategy, namely her uncompromising support for the UK.

Davidson had repositioned her party as a supporter of greater devolution to Holyrood, but Cameron instead unveiled the 'Carlisle principle', a hazy declaration founded on the idea that Scottish Government decisions should not disadvantage the UK.

One Tory source said: "It was like a tug of war contest. Ruth pulled in one direction and Cameron did the opposite."

In the end, Cameron's strategy delivered a Tory majority but held back progress in Scotland.

Of the party's three target seats, West Aberdeenshire and Kincardine fell comfortably to the Nationalists, Mundell held on by around 800 voters, and MSP John Lamont narrowly failed in the Borders.

Lord Forsyth, who was John Major's Scottish Secretary, complained the Cameron approach risked harming the UK.

"We've had the dilemma for Conservatives, which is they want to be the largest party at Westminster and therefore some see the fact that the nationalists are going to take seats in Scotland will be helpful. But that is a short-term and dangerous view which threatens the integrity of our country."

Cameron's divisive strategy could also reopen the old wound of Scottish Tory autonomy from the UK party.

Davidson, once a sceptic of loosening the ties with London, may now have no option but to back a radical internal restructuring if she wants successful photo-shoots to translate into votes.