Andrew Whitaker: In a crowded field of runners to be next Scots Tory leader, a dark horse may just emerge as the best bet

Annabel Goldie's departure as Scottish Conservative leader this coming autumn means the race is on for a successor, even if none of the possible candidates has officially declared.

While the Scottish Tories didn't have a disastrous election – compared with the Lib Dems, for example – the party did still emerge from the Holyrood polls with two fewer MSPs than it had in the last parliament.

The big challenge for whoever takes on what could be viewed as a poisoned chalice is to avoid what appears to be a managed decline in the party's fortunes north of the Border.

True, the party has a core vote that remained loyal during the excesses of Thatcherism and the Tory meltdown during the early years of New Labour's ascendancy, but that rapidly ageing part of the electorate won't be around forever.

The question is: which of the potential successors to Miss Goldie would be best placed to reverse this managed decline?

Deputy leader Murdo Fraser is clearly the front-runner to take over and will be hard to stop in any ballot of the party's Scottish membership.

He is also widely regarded as one of the best performers in all parties at Holyrood and his combative approach could mean he would be able to land a few punches on Alex Salmond during First Minister's Questions, even with the SNP's leader's thumping parliamentary majority.

But there's an issue as to whether Mr Fraser would be able to appeal to non-Tory voters.

Another candidate who seems certain to run is the party's justice spokesman, John Lamont, who has said the party "needs a winner" to make progress in Scotland – pointing to him being one of only three Tory MSPs to win a constituency rather than a list seat at Holyrood.

Mr Lamont could potentially choose the dynamic, newly-elected Glasgow list MSP Ruth Davidson as his deputy if he wins a leadership election, giving the party a modernising outlook.

However, it could be argued that Mr Lamont is too untried to take over as leader and would be too big a gamble.

That leaves the party's transport spokesman, Jackson Carlaw, who is likely to stand. But, again, it's hard to see him shaking things up too much.

One dark horse among the party's ranks at Holyrood is the finance spokesman and Lothians MSP Gavin Brown.

He is an accomplished performer at Holyrood and has the very real advantage in Scotland of not looking and sounding like a Tory – meaning he is potentially the only candidate who could win more votes for the party and reverse what must seem to many as an inevitable decline and an increasingly diminishing Holyrood presence.

However, whether Mr Brown will opt to stand in what already appears to be a crowded field of would-be Tory leaders remains to be seen.