Developers are attempting to hijack the planned rebirth of the Old Royal High for educational purposes by warning it will pose a much greater risk than the Â£75 million Rosewood scheme.
Duddingston House Properties and the Urbanist Group, the two firms behind the long-delayed hotel project, have submitted new analysis of the rival schemes, commissioned from engineering firm Arup, to the city council.
Fears have been raised over the “unnecessary and irreversible” loss of “substantial” parts of the 1829 building to accommodate a new home for Scotland’s only independent music school, St Mary’s, and the impact of construction works, including rock blasting and excavations if the Â£35m project goes ahead.
The plans already have the council’s backing, but it is tied to a lease agreement with the hotel developers following a design contest staged in 2009.
The hotel scheme was rejected by the city council in December 2015 amid widespread fears over the impact of two multi-storey extensions which are needed for the 147 hotel bedrooms. Critics claim they would be the equivalent of “sticking Mickey Mouse ears on the Mona Lisa”.
Councillors are due to discuss scaled-backed plans for the hotel development next month. They are being opposed by two separate campaigns – run by heritage groups and supporters of the music school.
The Arup dossier states: “The music school proposal removes substantial parts of the original building structure and also excavates large volumes of basalt rock from beneath the building.
"These demolitions and rock excavations can place the existing building fabric at significant risk during construction if not properly managed.
"The hotel designs seek to prioritise the conservation of the existing building, keeping sensitive rock blasting requirements away from the building and not undertaking large demolitions.”
In a new submission, the hotel developers have told the council: “The [music school] proposal fails to indicate the true nature and extent of the demolitions proposed, causing real concerns as to the endangerment of the Hamilton building and loss of heritage assets.
"The proposal has been portrayed as conservation-led when it is in fact harmful to the special interest of the building and highly risky if it were attempted. Public access is founded on the destruction of large sections of the original structure.”
Last month the Royal High School Preservation Trust, which is pursuing the music school scheme, released details of an opinion poll showing that 80 per cent of people supported their scheme.
Just 10 per cent were said to be in favour of the rival hotel project, according to the Ipsos Mori survey.
A spokesman for the trust said: “This latest attack is pretty desperate stuff from a team who are clearly spooked.
“It appears that they haven’t read – or have chosen to ignore– our design statement, which covers all the issues raised.
"The 80 per cent of the people in Edinburgh who support our scheme won’t be fooled by this sort of nonsense.”