Councillors unanimously rejected the application to transform the A-listed building on Calton Hill into a 127-room luxury hotel in August amid concerns it would harm the historic nature of the site and the landscape of the city.

Planning officers had earlier recommended the application from Duddingston House Properties and Urbanist Group be turned down due to its impact on the city’s heritage and landscape.

The consortium lodged an appeal against the decision with the Scottish Government’s planning and environmental appeals division and have appointed CMS partner Ann Faulds to assist them.

Ms Faulds, who is head of planning and transport at the legal firm, headed up Donald Trump’s legal team as the US President won approval for his golf course at Balmedie in Aberdeenshire.

She also previously advised the then Scottish Executive on its policies for compulsory purchases of land for development.

The City of Edinburgh Council owns the 19th century building, designed by Scottish architect Thomas Hamilton, but it has been leased long-term to the developers.

An initial £75 million plan for a hotel at the site was rejected in 2015 but the revised proposal would still have involved demolishing parts of the building to create wings for rooms.

The Scottish Government said that its planning officials will study four appeals by the developers, including two appeals over the council’s refusal to give listed building consent, in tandem.

A spokeswoman said the appeals will be “conjoined” but “decided on their own merits”.

The developers say the hotel development would create 250 new jobs and boost the economy by £35m.

David Orr, co-founder of Urbanist Hotels, said: “In line with our contractual agreement with City of Edinburgh Council, we remain wholly committed to bringing a world class hotel to the old Royal High School site.

“We fully recognise the importance of Hamilton’s Old Royal High School Building, and its setting, on a national and international level, and remain committed to reviving a building which has failed to have a credible and sustainable use for nearly 50 years.”

He added: “Our proposals guarantee the future of Hamilton’s masterpiece, both architecturally and financially, and we feel that the appeals process will allow many of the complex technical issues raised with both previous planning applications to be thoroughly presented and cross-examined.

“We welcome the chance to constructively move forward with this tourism-led flagship project - delivering much-needed investment, jobs and new opportunities to Edinburgh and Scotland.”