T in the Park is at the centre of a cronyism row after it emerged a former SNP adviser working for the festival helped it secure a £150,000 grant from the Scottish Government.

Jennifer Dempsie, a project manager for promoters DF Concerts Ltd, brokered the initial meeting between the company boss Geoff Ellis and Culture Secretary Fiona Hyslop to discuss the extra funding.

The discussion on May 28 ultimately led to Ms Hyslop signing off an an “ad hoc state aid” package for the festival on July 2 eight days before it began.

Ms Dempsie, the partner of SNP Westminster leader Angus Robertson, had been a special adviser to First Minister Alex Salmond from 2007 to 2009, then worked for the SNP for four years before becoming a public relations consultant.

The money was justified as support for festival's relocation from its traditional home in Balado in Perth and Kinross following environmental concerns, to Strathallan Castle.

Ministers have described it as “one-off grant funding support of £150,000… to help ensure the successful transition of this iconic music festival to their new temporary site at Strathallan”.

However the award of public funds to a commercial event has been questioned by the Scottish Conservatives.

DF Concerts Ltd is 78 per cent owned by London-based LN-Gaiety Holdings Ltd, which last year had a turnover of £167 million and a pre-tax profit of £9m.

Ms Dempsie is currently campaigning to become an SNP list MSP in the Highlands and Islands.

While the state aid deal was being assessed by the government, Ms Hyslop publicly endorsed her, writing on her Facebook page: “Good luck Jen , you'd make a formidable SNP candidate and a great asset to the Scottush (sic) Parliament.”

Willie Rennie, leader of the Scottish LibDems and a list MSP for Mid-Scotland and Fife, said: “T in the Park has been great for Perth and Kinross and the whole of Scotland, but as a thriving business people will also want assurances that its success is not being built on the foundations of cronyism. £150,000 is a significant sum of money, so any state aid funding must be distributed fairly and transparently.

“I hope the Culture Secretary will move quickly to explain the full details behind this situation."

Liz Smith, a Conservative list MSP for the region, added: “All the facts have to be put on the table. There’s been a considerable lack of transparency about the whole process.”

A T in the Park spokeswoman said: “Jennifer was employed as project manager on a short term contract to help with the T in the Park site relocation.

“She set up a meeting between Geoff Ellis and Fiona Hyslop which took place on 28th May 2015, at which they discussed funding.

“Jennifer did not attend this meeting or have any other involvement.

“We have invested a seven-figure sum in bringing [T in the Park] to Strathallan."

She pointed out the event has pumped hundreds of millions of pounds into the Scottish economy since it began in 1994.

The spokeswoman added: “We're grateful that ministers recognised the event's importance with this payment to support the massive operational investment.”

A government spokesman confirmed Ms Dempsie’s involvement, adding that she had supported DF Concerts’ request to seek a meeting with the Scottish Government.

Ms Dempsie did not respond.